Fibers of variable wettability and materials containing the fibers

ABSTRACT

The present invention is directed to an absorbent material and the fibers therein, having two or more layers including an upper surface layer which has on the outer surface of the layer one or more surface area zones which are more wettable zones and adjacent thereto one or more less wettable zones, where the more wettable zones have a greater hydrophilicity than the less wettable zone. The present invention is also directed to the fibers therein, which contain polyvalent cation-containing compounds and fatty acid containing compounds. The present invention also provides for methods of treating fibers or solid materials and processes of producing the hydrophobic materials.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application SerialNo. PCT/US04/043030, filed Dec. 20, 2004, which claims priority to U.S.Provisional Application Ser. No. 60/531,706, filed Dec. 19, 2003 andU.S. Provisional Application Ser. No. 60/569,980, filed May 10, 2004,each of which are incorporated by reference in their entireties herein,and from which priority is claimed.

FIELD OF THE INVENTION

The present invention is directed to an absorbent material, and thefibers therein, having variable wettability for the control of waterabsorption on the surface of the material.

BACKGROUND OF THE INVENTION

It has long been desirable to be able to control the surfacecharacteristics of textiles and fabrics including nonwoven materials. Aparticularly important characteristic is whether a material readilyabsorbs or repels water at its surface. For fibers used to make nonwovenmaterials for use in personal care products and for many other uses, therelative hydrophobicity or hydrophilicity of the fiber itself, and thematerial made from it, is of great importance in determining where andhow they can be used.

When brought into contact with the surface of a material, water prefersto wet some surfaces and prefers to bead on others. A surface can beclassified as hydrophilic, with a water contact angle less than 90°, orhydrophobic, with a water contact angle greater than 90°, based on theshape that a drop of water assumes when placed on that surface.

Fabric water repellency and breathability have been studied for severaldecades (A. W. Adamson, Physical Chemistry of Surfaces, Second Edition,Wiley, 1967, Chapters VII and X). A nonwoven web of fibers can bemodeled as a bundle of cylindrical pores (capillaries) of radius r. Thefluid pressure required to penetrate the interfiber pores of a nonwovenweb can be approximated from Laplace's equation for the penetration of afluid into a tube as follows: P=(2 γ cos θ)/r

where:

P=pressure required to push fluid through the tube;

γ=fluid surface tension;

θ=advancing contact angle; and

r=pore radius.

See Dutkiewicz, J., Nonwoven Structures for Absorption of Body Fluids,sub-chapter 2.1. Basic Structural Properties of Absorbent Networks,pages 7-37 (published by Edana, Brussels, Belgium) (2003). This equationcan be used to describe web wetting (θ<90°, P is positive) or web waterrepellency (θ>90°, P is negative). In the case of water repellency, thefluid will not wet the web unless a pressure of P is applied to push thefluid into the web.

From the equation, barrier quality is predicted to be enhanced byincreasing the contact angle with a water-repellent finish. In otherwords, the pores of the web should be rendered as hydrophobic aspossible.

Apparent contact angles can be increased by surface roughness on themacroscale and microscale. Application of a waterproofing agent thatcauses microscopic pore surface roughness will lead to an increase inapparent contact angle, thus improving barrier quality.

From the equation, barrier quality is predicted to be enhanced byreducing the size of the interfiber pores. Ideally, the web should be asstrong as possible. As pressure builds, weakness in the web will causedeformation, and deformation increases r, thus lowering pressure P. Webstrength can be enhanced, for example, by increasing the amount ofbinder in the web.

The size of interfiber pores in a fibrous web is determined by the fibersize and the density or extent of compaction of the web. Increasing thedensity of the web can reduce the size of interfiber pores, or usingsmaller diameter fibers at the same density can reduce them. Smallerfibers pack together more efficiently in a densified web, resulting insmaller interfiber pores. From the equation, using smaller fibers servesto decrease r, thus raising pressure P.

Filler material can be added to an absorbent material to reduce the sizeof interfiber pores. From the equation, the addition of filler alsoserves to decrease r, thus raising pressure P.

From the equation, hydrophobicity and barrier quality is predicted to bedirectly proportional to the fluid surface tension. The barriertreatment should be as durable as possible. Any additives in the barriertreatment that will dissolve in the fluid coming in contact with thesurface of the material will likely lower its surface tension, thuslowering pressure P.

SUMMARY OF THE INVENTION

The present invention provides for an absorbent material with two ormore layers, including an upper layer which has on the outer surface oneor more surface area zones. These zones include more wettable zoneshaving greater hydrophilicity adjacent to less wettable zones. Thetreatment of the fibers in the absorbent material allow for the variablewettability of the present invention.

In certain aspects of the invention, the absorbent materials have morewettable zones with a total surface area which is from about 5 percentto about 95 percent of the upper surface layer. In a preferredembodiment, the more wettable zones have a total surface area which isfrom about 10 percent to about 90 percent of the upper surface layer,even more preferred, from about 30 percent to about 70 percent of theupper surface layer.

In another aspect of the invention, the more wettable zones of theabsorbent material have elements in a pattern which are all connected,the elements of the pattern essentially isolating the less wettablezones from each other. Likewise, in another aspect of the invention, theless wettable zones have elements in a pattern which are all connected,the elements of the pattern essentially isolating the more wettablezones from each other.

In the absorbent material of the present invention, the less wettablezones of the upper surface layer contain a polyvalent metal ion salt ofa fatty acid. In one embodiment of the invention, the more wettablezones of the absorbent material contain a polyvalent metal ion salt of afatty acid and where the concentration of the polyvalent metal ion saltof a fatty acid is greater in the less wettable zones.

The present invention also provides for absorbent materials where theless wettable zones of the upper surface layer are located onprotrusions which project above the surface of the material and the morewettable zones are located in indentations which project below thesurface of the material. In another embodiment, the absorbent materialhas an upper less wettable layer and adjacent thereto a lower morewettable layer, where the upper less wettable layer has protrusionswhich project above the surface of the material and are at a greaterdistance from the lower layer than indentations which project below thesurface of the upper layer and which are closer to the lower layer.

In yet another embodiment of the invention, the absorbent material is inthe form of a sheet having an upper surface and opposite thereto a lowersurface, where the entire upper surface is more wettable than the lowersurface. In one aspect of this embodiment, the lower surface hasdisposed thereon a reaction product of a polyvalent cation-containingcompound and a fatty acid containing compound.

In one aspect the present invention provides fibers bound with apolyvalent cation-containing compound and coated thereon with a fattyacid containing compound. In one embodiment, the fatty acid containingcompound is present in an amount of from about 0.01 weight percent toabout 5 weight percent based on the weight of the treated fiber,preferably from about 0.01 weight percent to about 3 weight percentbased on the weight of the treated fiber, more preferably from about0.05 weight percent to about 1.5 weight percent based on the weight ofthe treated fiber, and even more preferred, from about 0.1 weightpercent to about 1 weight percent based on the weight of the treatedfiber. In certain aspects of the invention, the fatty acid containingcompound is selected from the group consisting of sodium oleate, methyloleate, sodium laurate, oleic acid, stearic acid, and mixtures thereof.

In one embodiment, the polyvalent cation-containing compound is presentin an amount from about 0.1 weight percent to about 20 weight percentbased on the dry weight of the untreated fiber, preferably from about 2weight percent to about 12 weight percent based on the dry weight of theuntreated fiber, more preferably from about 3 weight percent to about 8weight percent based on the dry weight of the untreated fiber. In oneaspect of the invention, the polyvalent cation containing compound is apolyvalent metal ion salt, preferably selected from the group consistingof aluminum, iron, tin, salts thereof, and mixtures thereof. In apreferred embodiment, the polyvalent metal is aluminum. In otherembodiments, the polyvalent salt is selected from the group consistingof aluminum chloride, aluminum hydroxide, aluminum sulfate, and mixturesthereof.

In one embodiment, the polyvalent cation-containing compound and fattyacid containing compound are directly applied to the fibers at atemperature close or above the melting point of the fatty acid. In oneembodiment, the temperature ranges between about 110 to about 115degrees Celsius.

The fatty acid may also be a component of a carrier in the form ofparticles. In one embodiment, the carrier is a type of fiber. In apreferred embodiment, the carrier is made of synthetic fibers. Thecarrier is blended with the cellulosic fibers and cured at a temperatureto allow the carrier to melt or change into vapor.

In another embodiment of the invention, the fibers may further comprisea separate carrier. In certain embodiments, the carrier may be a type offibers, preferably a polypropylene fiber. In one embodiment, the carriercomprises an acid. In a specific embodiment, the acid is stearic acid.

The fatty acid migrates and interacts or reacts with the cation on thesurface of the fiber, forming as a reaction product a fatty acid salt.Migration can be accelerated or enhanced by heat. Thus, the fibers canbe used to produce a fibrous material containing fibers which havedisposed on the surface of the fiber a reaction product of a polyvalentcation-containing compound and a fatty acid containing compound. Fattyacid salts of polyvalent cations are generally characterized as having avery low water solubility or as being insoluble. In one form thesematerials are widely known as “bathtub ring”. These materials are knownwaterproofing materials because of their hydrophobicity.

In the present invention, the contact angle of the fibers is equal to orgreater than 90 degrees.

In another embodiment, the fibers further have a compound selected fromthe group consisting of an acid, a buffer salt, an insoluble metalhydroxide, and combinations thereof. Preferably, the compound is an acidmore preferably a weak acid. In a preferred embodiment, the acid iscitric acid. In one embodiment, the compound is present in an amount offrom about 0.5 weight percent to about 10 weight percent based on thedry weight of the treated fibers, preferably from about 0.5 weightpercent to about 3 weight percent based on the dry weight of the treatedfibers.

In another aspect of the invention, the fibers also contain a reducingagent.

The fibers of the present invention may also be cross-linked optionallywith treatment of a cross-linking agent. The fibers may be cross linkedbefore, during, or after the fatty acid treatment. In one embodiment,the cross-linking agent is selected from the group consisting offormaldehyde, formaldehyde addition products, dialdehyde agents, andpolycarboxylic acids. In another embodiment, the cross-linking agent isglutaraldehyde. In one aspect, the cross-lining agent is applied withthermal radiation.

In another aspect of this invention, the fibers are preswelled with aswelling agent prior to application of the fatty acid. In oneembodiment, the swelling agent is a polyvalent metal salt, preferablysodium hydroxide.

The invention also provides for fibers treated with a polyvalent cationsalt of a fatty acid directly applied to the fibers at a temperatureclose or above the melting point of the fatty acid. In one embodiment,the polyvalent cation salt is aluminum stearate. In another embodiment,the temperature ranges between about 110 to about 115 degrees Celsius.

In another aspect of this invention there is provided a blend of fiberscomprising:

(A) fibers bound with a polyvalent cation-containing compound, and

(B) fibers coated with a fatty acid containing compound.

The invention also provides for fibrous material containing fibers whichhave disposed on the surface of the fiber a reaction product of apolyvalent cation-containing compound and a fatty acid containingcompound. The fibrous material may also have one or more fillers.

The present invention also provides for a process of producing ahydrophobic fibrous material by:

-   -   (I) forming a fibrous material containing fibers bound with a        polyvalent cation-containing compound and placing thereon a        fatty acid containing compound, or    -   (II) forming a fibrous material containing a blend of fibers        having        -   (A) fibers bound with a polyvalent cation-containing            compound, and        -   (B) fibers coated with a fatty acid containing compound, and    -   (III) curing the material so that the polyvalent        cation-containing compound and the fatty acid containing        compound interact to form a product that renders the fibrous        material hydrophobic.

In yet another aspect, the invention provides for a method for treatinga solid material with a polyvalent metal containing compound and with afatty acid containing compound, wherein the fatty acid containingcompound is applied to the solid material in the form of amicrodispersion; and a stream of gas is applied to the microdispersionof the fatty acid containing compound, so that the bonding of the fattyacid containing compound to the surface of the solid material is carriedout by diffusion of the fatty acid containing compound in aheterogeneous medium onto all the surface of the solid material andreaction of the fatty acid containing compound with polyvalent metalcontaining compound bonded to the surface of the solid material. In oneembodiment, the treatment of the surface of the solid material with apolyvalent metal containing compound is accomplished before thetreatment of the surface of the solid material with a fatty acidcontaining compound in two separate steps. In another embodiment, thetreatments are carried out in a continuous process. In order to producea microdispersion of a fatty acid containing compound in one embodiment,a quantity of liquid composition of the fatty acid containing compoundis applied in contact with the surface of the solid material.

In one method of the invention, the stream of gas is applied to thesurface of the solid material. In another method, a stream of gas isapplied to the solid material at the same time as a microdispersion of afatty acid containing compound is produced. The gas is selected from thegroup consisting of ambient air, nitrogen, helium, carbon dioxide, andcombinations thereof.

In one embodiment of the method, a microdispersion of the fatty acidcontaining compound is produced on the solid material before applying astream of gas to the solid material. In another embodiment, amicrodispersion of a fatty acid containing compound is produced byspraying directed towards the surface of the solid material. In yetanother embodiment, the microdispersion of the fatty acid is applied invapor form.

In another embodiment of the method, a microdispersion of a fatty acidcontaining compound is produced by contacting the surface of a firstface of a solid support previously loaded with a liquid composition ofthe fatty acid containing compound. In another embodiment, amicrodispersion of a fatty acid containing compound is produced bywetting the surface of the solid material with a liquid compositionformed of a solution of the fatty acid containing compound in a volatileneutral solvent.

In one aspect of the invention, the solid support is selected from thegroup consisting of an absorbent pad, a non-absorbent pad, a rollerdriven in rotation, a brush, and mixtures thereof. The solid is wet byimmersion in a bath of the liquid composition in one aspect.

In another aspect of the invention, the stream of gas is directedtowards the surface of the solid material with a positive velocitycomponent perpendicular to the surface of the solid material. Thesurface of the solid material is placed in a treatment space adaptedaccording to the characteristics of the gas stream such that anyquantity of gas flow coming from the solid material which can be onceagain returned to the solid material by the gas stream is negligible.

The invention also provides a method for forming a fibrous webcontaining first and second fibrous component, wherein a first componentis treated with a fatty acid containing compound; a second component istreated with a polyvalent metal containing compound; and a stream of gasis applied to the fibrous web at a temperature allowing the fatty acidcontaining compound to transform to a vapor, so that the bonding of thefatty acid containing compound to the second component is carried out bydiffusion of the fatty acid containing compound in a vapor state ontothe second component and reaction of the fatty acid containing compoundwith polyvalent metal containing compound bonded to the secondcomponent. In one embodiment the polyvalent metal containing compound isreplaced with a polyvalent organic cation.

Any of the methods of the invention may be used to treat a natural orartificial fiber or fibrous structure.

Various applications of the processes include obtaining a solidcomposition in a divided form, capable of absorbing hydrocarbons, andhaving a density of less than that of water. Another application is fortreating paper. Yet another application of the processes of theinvention are for treating the surface of glass.

DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, and 1C represent the application of a foam coating onrepresentative handsheets. FIG. 1A shows the foaming effect on ahandsheet designated Web#2. FIG. 1B shows the foaming effect onhandsheet Web#1. FIG. 1C shows an uncolored stain hide using the sameWeb#2, but without the blue pigment.

FIG. 2 represents a handsheet designated Web#3 with a profiled formingscreen having protrusion patterns as reflected in the material produced.

FIG. 3A illustrates an example of more wettable and less wettable zoneswith the use of a hydrophobic polymer containing a blue pigment. FIG. 3Billustrates uniform wettability in a handsheet without a texturedsurface.

FIG. 4A illustrates an example of the structure of the invention, whichis composed of an upper acquisition layer (AL) and a bottom storagelayer (SL). FIG. 4B illustrates a structure comprising an upper layerhaving flat surface and being wettable on its whole area.

FIGS. 5A and 5B illustrate a top FIT board. FIG. 5A is an image of thetop view and FIG. 5B is an image of the side view of the board. Bothfigures show the length of the upper board as 29.7 cm with the tuberepresented by (9).

FIG. 6 illustrates the alignment of the tested sample (10) and thestorage layer (11).

FIG. 7 illustrates the top surface of a sheet before and after a coloredliquid was applied on its surface. The figure shows the masking effectproduced by the treatment of the sheet.

FIG. 8 shows a sample of solid material placed under a rotating fan.

FIG. 9 shows a device, which can be used for continuous production of ahydrophobic sheet.

FIG. 10 shows another variant of a device, which can be used to producea solid material with hydrophobic surface.

FIG. 11 shows the contact angle between a water droplet meniscus and thesurface of the cellulose sheet. FIG. 11( a) shows the angle greater than90 degrees demonstrating a hydrophobic surface. FIG. 11( b) shows theangle less than 90 degrees demonstrating a hydrophilic surface.

FIG. 12 shows the contact angle of various handsheets coated with soapsolutions differing by acid type. The contact angle is shown overincreasing aluminum content in ppm.

DETAILED DESCRIPTION

The absorbent materials of the present invention provide for multiplelayers, including an upper layer with an outer surface of variablewettability zones. The fibers of the less wettable zones are treatedwith polyvalent-cation compounds and fatty acid compounds.

Cellulose Fibers

Cellulosic fibrous materials suitable for use in the present inventioninclude softwood fibers and hardwood fibers. See M. J. Kocurek & C. F.B. Stevens, Pulp and Paper Manufacture—Vol. 1: Properties of Fibrous RawMaterials and Their Preparation for Pulping, The Joint TextbookCommittee of the Paper Industry, pp. 182 (1983), which is herebyincorporated by reference in its entirety. Exemplary, though notexclusive, types of softwood pulps are derived from slash pine, jackpine, radiata pine, loblolly pine, white spruce, lodgepole pine,redwood, and douglas fir. North American southern softwoods and northernsoftwoods may be used, as well as softwoods from other regions of theworld. Hardwood fibers may be obtained from oaks, genus Quercus, maples,genus Acer, poplars, genus Populus, or other commonly pulped species. Ingeneral, softwood fibers are preferred due to their longer fiber lengthas measured by T 233 cm-95, and southern softwood fibers are mostpreferred due to a higher coarseness as measured by T 234 cm-84, whichleads to greater intrinsic fiber strength as measured by breaking loadrelative to either northern softwood or hardwood fibers.

The fibrous material may be prepared from its natural state by anypulping process including chemical, mechanical, thermomechanical (TMP)and chemithermomechanical pulping (CTMP). These industrial processes aredescribed in detail in R. G. Macdonald & J. N. Franklin, Pulp and PaperManufacture in 3 volumes; 2^(nd) Edition, Volume 1: The pulping of wood,1969; Volume 2: Control, secondary fiber, structural board, coating,1969; Volume 3: Papermaking and paperboard making, 1970, The jointTextbook Committee of the Paper Industry, and in M. J. Kocurek & C. F.B. Stevens, Pulp and Paper Manufacture, Vol. 1: Properties of FibrousRaw Materials and Their Preparation for Pulping, The Joint TextbookCommittee of the Paper Industry, 1983, 182 pp., both of which are herebyincorporated by reference in their entirety. Preferably, the fibrousmaterial is prepared by a chemical pulping process, such as a Kraft orsulfite process. In particular the Kraft process is especiallypreferred. Pulp prepared from a southern softwood by a kraft process isoften called SSK. In a similar manner, southern hardwood, northernsoftwood and northern hardwood pulps are designated SHK, NSK and NHK,respectively. Bleached pulp, which is fibers that have been delignifiedto very low levels of lignin, are preferred, although unbleached kraftfibers may be preferred for some applications due to lower cost,especially if alkaline stability is not an issue. Desirably, thechemically treated cellulose fiber has been derived from a source whichis one or more of Southern Softwood Kraft, Northern Softwood Kraft,hardwood, eucalyptus, mechanical, recycle and rayon, preferably SouthernSoftwood Kraft, Northern Softwood Kraft, or a mixture thereof, morepreferably, Southern Softwood Kraft.

Pulp consistency is a pulp-industry specific term which is defined asthe bone dry fiber amount divided by the total amount which includesfiber, water, other solids, etc. and multiplied by 100 percent.Therefore, for a slurry of 12 percent consistency, every 100 kilogramsof slurry would contain 12 bone dry kilograms of fiber.

Chemically Treated Cellulose Fibers

As used herein, the phrase “chemically treated” cellulose fiber ornon-cellulose fiber means a fiber that has been treated with apolyvalent metal-containing compound to produce a fiber with apolyvalent metal-containing compound bound to it.

It is not necessary that the compound chemically bond with the fibers,although it is preferred that the compound remain associated in closeproximity with the fibers, by coating, adhering, precipitation, or anyother mechanism such that it is not dislodged from the fibers duringnormal handling of the fibers. For convenience, the association betweenthe fiber and the compound discussed above may be referred to as thebond, and the compound may be said to be bound to the fiber. It isnecessary that the interaction of the materials used to produce thepolyvalent metal-containing compound in proximity to the fibers or thatthe polyvalent metal-containing compound itself, dissociate intoindividual ions, preferably in an aqueous environment, and that the ionsthen contact individualized cellulose fibers. For example, sheetedcellulosic fibers treated with a water insoluble aluminum compound havethe same aluminum concentration before and after hammer milldisintegration with a Kamas mill. Likewise, sheeted cellulosic fiberstreated with a water soluble aluminum compound have the same aluminumconcentration before disintegration with a Kamas mill and afterdisintegration with a Kamas mill. In addition, sheeted cellulosic fiberstreated with a water insoluble and a water soluble aluminum compoundhave the same aluminum concentration before disintegration with a Kamasmill and after disintegration with a Kamas mill.

One type of chemically treated cellulose fiber which was originallydeveloped for use in absorbent structures is described in U.S. Pat. No.6,562,743 and a published counterpart, WO 00/38607, both of which arehereby incorporated by reference in their entirety. This fiber isavailable as CARESSA® from Buckeye Technologies Inc. of Memphis, Tenn.When used in absorbent structures, the chemically treated cellulosefiber has associated with it a weak acid. When used in otherapplications, for the fibers of this invention, it may be used with anassociated weak acid, or in an alternative embodiment, it may be usedwithout the associated weak acid.

The requirement that the polyvalent metal-containing compound be able todissociate into individual ions or is formed from individual ions,preferably in an aqueous environment, and that the ions then contactindividualized cellulose fibers, eliminates from further considerationas potentially useful as the polyvalent metal-containing compound ofthis invention many polyvalent metal-containing compounds and the fiberstreated therewith, such as, for example, various clays used to treatfibers in paper making.

The chemically treated cellulose fiber or the chemically treatednon-cellulosic fiber of this invention is treated with from about 0.1weight percent to about 20 weight percent of the polyvalentmetal-containing compound, based on the dry weight of the untreatedfiber, desirably with from about 2 weight percent to about 12 weightpercent of the polyvalent metal-containing compound, and preferably withfrom about 3 weight percent to about 8 weight percent of the polyvalentmetal-containing compound.

Any polyvalent metal salt including transition metal salts may be used,provided that the compound is capable of increasing the stability of thecellulose fiber or the chemically treated non-cellulosic fiber in analkaline environment. Examples of suitable polyvalent metals includeberyllium, magnesium, calcium, strontium, barium, titanium, zirconium,vanadium, chromium, molybdenum, tungsten, manganese, iron, cobalt,nickel, copper, zinc, aluminum and tin. Preferred ions include aluminum,iron and tin. The preferred metal ions have oxidation states of +3 or+4. The most preferred ion is aluminum. Any salt containing thepolyvalent metal ion may be employed. Examples of suitable inorganicsalts of the above metals include chlorides, nitrates, sulfates,borates, bromides, iodides, fluorides, nitrides, perchlorates,phosphates, hydroxides, sulfides, carbonates, bicarbonates, oxides,alkoxides phenoxides, phosphites, and hypophosphites. Examples ofsuitable organic salts of the above metals include formates, acetates,butyrates, hexanoates, adipates, citrates, lactates, oxalates,propionates, salicylates, glycinates, tartrates, glycolates, sulfonates,phosphonates, glutamates, octanoates, benzoates, gluconates, maleates,succinates, and 4,5-dihydroxy-benzene-1,3-disulfonates. In addition tothe polyvalent metal salts, other compounds such as complexes of theabove salts include amines, ethylenediaminetetra-acetic acid (EDTA),diethylenetriaminepenta-acetic acid (DIPA), nitrilotri-acetic acid(NTA), 2,4-pentanedione, and ammonia may be used. Preferred salts arealuminum chloride, aluminum hydroxide and aluminum sulfate.

Alum is an aluminum sulfate salt which is soluble in water. In anaqueous slurry of cellulose, some of the alum will penetrate the fibercell wall, but since the concentration of ions is low, most of thedissolved aluminum salt will be outside the fiber. When the pH isadjusted to precipitate aluminum hydroxide, most of the precipitateadheres to the fiber surface.

In one embodiment of this invention, the chemically treated cellulosefiber or the chemically treated non-cellulosic fiber has an acid boundor otherwise associated with it. A variety of suitable acids may beemployed, although the acid preferably should have a low volatility, andbond to the fiber. Strong mineral acids are not suitable, and,preferably, the acid used in the practice of this aspect of thisinvention is a weak acid. Examples include inorganic acids such assodium bisulfate, sodium dihydrogen phosphate and disodium hydrogenphosphate, and organic acids such as formic, acetic, aspartic,propionic, butyric, hexanoic, benzoic, gluconic, oxalic, malonic,succinic, glutaric, tartaric, maleic, malic, phthallic, sulfonic,phosphonic, salicylic, glycolic, citric, butanetetracarboxylic acid(BTCA), octanoic, polyacrylic, polysulfonic, polymaleic, andlignosulfonic acids, as well as hydrolyzed-polyacrylamide and CMC(carboxymethylcellulose). Among the carboxylic acids, acids with twocarboxyl groups are preferred, and acids with three carboxyl groups aremore preferred. Of these acids, citric acid is most preferred.

In general, the amount of acid employed is dictated by the acidity andthe molecular weight of that acid. Generally, it is found that anacceptable range of acid application is from about 0.5 weight percent ofthe fibers to about 10 weight percent of the fibers. As used herein, the“weight percent of the fibers” refers to the weight percent of dry fibertreated with the polyvalent metal containing compound. For citric acid,the preferred range of application is from about 0.5 weight percent toabout 3 weight percent of the fibers. A preferred combination is analuminum-containing compound and citric acid. For the chemically treatedfibers of this aspect of this invention, it is desirable that the weakacid content of the chemically treated fibers is from about 0.5 weightpercent to about 10 weight percent based on the dry weight of thetreated fibers, more desirably, from about 0.5 weight percent to about 5weight percent based on the dry weight of the treated fibers, and,preferably, from about 0.5 weight percent to about 3 weight percentbased on the dry weight of the treated fibers.

Within the scope of this aspect of this invention is the use of buffersalts rather than a weak acid in combination with the polyvalentmetal-containing compound. Any buffer salt that in water would provide asolution having a pH of less than about 7 is suitable. Examples of theseare sodium acetate, sodium oxalate, sodium tartrate, sodium phthalate,sodium dihydrogen phosphate, disodium hydrogen phosphate and sodiumborate. Buffer salts may be used in combination with their acids in acombination that in water would provide a solution having a pH of lessthan about 7, for example, oxalic acid/sodium oxalate, tartaricacid/sodium tartrate, sodium phthalate/phthalic acid, and sodiumdihydrogen phosphate/disodium hydrogen phosphate.

In a further variation of this invention, the polyvalentmetal-containing compound is used in combination with an insoluble metalhydroxide, such as, for example, magnesium hydroxide, or in combinationwith one or more alkali stable anti-oxidant chemicals or alkali stablereducing agents that would inhibit fiber degradation in an alkalineoxygen environment. Examples include inorganic chemicals such as sodiumsulfite, and organic chemicals such as hydroquinone.

For the chemically treated fibers of this aspect of this invention, incombination with the polyvalent metal-containing compound, it isdesirable that the buffer salt content, the buffer salt weak acidcombination content, the insoluble metal hydroxide content and/or theantioxidant content of the chemically treated fibers is from about 0.5weight percent to about 10 weight percent based on the dry weight of thetreated fibers, more desirably, from about 0.5 weight percent to about 5weight percent based on the dry weight of the treated fibers, and,preferably, from about 0.5 weight percent to about 3 weight percentbased on the dry weight of the treated fibers.

If desired, reducing agents may be applied to the treated fibers tomaintain desired levels of fiber brightness, by reducing brightnessreversion. The addition of acidic substances may cause browning offibers when heated during processing of webs containing the fibers.Reducing agents counter the browning of the fibers. The reducing agentshould also bond to the fibers. Preferred agents are sodiumhypophosphite and sodium bisulfite and mixtures thereof.

The fibers suitable for use in the practice of this invention may betreated in a variety of ways to provide the polyvalent metalion-containing compound in close association with the fibers. Apreferred method is to introduce the compound in solution with thefibers in slurry form and cause the compound to precipitate onto thesurface of the fibers. Alternatively, the fibers may be sprayed with thecompound in aqueous or non-aqueous solution or suspension. The fibersmay be treated while in an individualized state, or in the form of aweb. For example, the compound may be applied directly onto the fibersin powder or other physical form. Whatever method is used, however, itis preferred that the compound remain bound to the fibers, such that thecompound is not dislodged during normal physical handling of the fiberbefore contact of the fiber with liquid.

In a preferred embodiment, the treated fibers of the present inventionare made from cellulose fiber known as FOLEY FLUFFS® from BuckeyeTechnologies Inc. (Memphis, Tenn.). The pulp is slurried, the pH isadjusted to about 4.0, and aluminum sulfate (Al₂(SO₄)₃) in aqueoussolution is added to the slurry. The slurry is stirred and theconsistency reduced. Under agitation, the pH of the slurry is increasedto approximately 5.7. The fibers are then formed into a web or sheet,dried, and, optionally, sprayed with a solution of citric acid at aloading of about 2.5 weight percent of the fibers. The web is thenpackaged and shipped to end users for further processing, includingfiberization to form individualized fibers useful in the manufacture ofvarious products.

In another preferred embodiment, the treated fibers of the presentinvention are made from cellulose fiber obtained from BuckeyeTechnologies Inc. (Memphis, Tenn.). The pulp is slurried, the pH isadjusted to about 4.0, and aluminum sulfate (Al₂(SO₄)₃) in aqueoussolution is added to the slurry. The slurry is stirred and theconsistency reduced. Under agitation, the pH of the slurry is increasedto approximately 5.7. The fibers are then formed into a web or sheet,dried, and sprayed with a solution of sodium oleate at a loading ofabout 1.0 weight percent of the fibers. The web is then packaged andshipped to end users for further processing, including re-slurrying toform a web useful in the manufacture of filtration products. If areducing agent is to be applied, preferably it is applied before adrying step and following any other application steps. The reducingagent may be applied by spraying, painting or foaming.

Metal ion content, including aluminum or iron content, in pulp samplesis determined by wet ashing (oxidizing) the sample with nitric andperchloric acids in a digestion apparatus. A blank is oxidized andcarried through the same steps as the sample. The sample is thenanalyzed using an inductively coupled plasma spectrophotometer, such as,for example, a Perkin-Elmer ICP 6500. From the analysis, the ion contentin the sample can be determined in parts per million. The polyvalentcation content desirably is from about 0.1 weight percent to about 5.0weight percent, based on the dry weight of the treated fibers, moredesirably, from about 0.1 weight percent to about 3.0 weight percent,based on the dry weight of the treated fibers, preferably from about 0.1weight percent to about 1.5 weight percent, based on the dry weight ofthe treated fibers, more preferably, from about 0.2 weight percent toabout 0.9 weight percent, based on the dry weight of the treated fibers,and more preferably from about 0.3 weight percent to about 0.8 weightpercent, based on the dry weight of the treated fibers.

Without intending to be bound by theory, it is believed that by thisprocess, the soluble Al₂(SO₄)₃ introduced to the pulp slurry isconverted to insoluble Al(OH)₃ as the pH is increased. The insolublealuminum hydroxide precipitates onto the fiber. Thus, the resultantchemically treated cellulose fibers are coated with Al(OH)₃ or containthe insoluble metal within the fiber interior.

The sodium oleate sprayed onto the web containing the fibers dries onthe fibers. When the Al(OH)₃-oleate treated fibers are formed into afilter based sheet, the aluminum and oleate ions create a hydrophobicenvironment in addition to increasing the wet strength of the structure.These results are exemplified in the procedures set forth below.

In another embodiment, hydrated aluminum sulfate and sodium oleate aresprayed on the fiber after the drying section of a paper machine. Inanother embodiment, hydrated aluminum sulfate and sodium oleate areprecipitated onto the fiber in the wet end section of a paper machine.In another embodiment, hydrated aluminum sulfate and sodiumhypophosphite are sprayed on the fiber prior to the pressing stage, andsodium oleate is sprayed after drying. In another embodiment, hydratedaluminum sulfate, sodium hypophosphite and sodium oleate are sprayed onthe fiber prior to the pressing stage. In yet another embodiment,hydrated aluminum sulfate is precipitated onto the fiber, hydratedaluminum and sodium hypophosphite are sprayed on the fiber prior topressing, and sodium oleate is sprayed on the fiber after drying. Inanother embodiment, hydrated aluminum sulfate is precipitated onto thefiber and sodium oleate is sprayed on the fiber prior to the pressingstage.

Various materials, structures and manufacturing processes useful in thepractice of this invention are disclosed in U.S. Pat. Nos. 6,241,713;6,353,148; 6,353,148; 6,171,441; 6,159,335; 5,695,486; 6,344,109;5,068,079; 5,269,049; 5,693,162; 5,922,163; 6,007,653; 6,355,079;6,403,857; 6,479,415; 6,562,742; 6,562,743; 6,559,081; 6,495,734;6,420,626; and in U.S. Patent applications with serial numbers andfiling dates, 09/719,338 filed Jan. 17, 2001; Ser. No. 09/774,248 filedJan. 30, 2001; and Ser. No. 09/854,179 filed May 11, 2001, all of whichare hereby incorporated by reference in their entirety.

All patents, patent applications, and publications cited in thisspecification are hereby incorporated by reference in their entirety. Incase of a conflict in terminology, the present disclosure controls.

Fatty Acid Containing Compounds

A very large number of natural and synthetic fatty acids and variousderivatives are known. Examples of some useful in the practice of thepresent invention are listed below:

Monocarboxylic, straight, saturated acids such as butyric, valeric,caproic, caprylic, pelargonic, capric, lauric, myristic, palmitic,margaric, stearic, arachidic, behenic, lignoceric, cerotic, carboceric,montanic, mellisic, lacceroic, ceromelissic, and geddic; monocarboxylic,straight, unsaturated acids such as palmitoleic, oleic, linoleic,alpha-linoleic, arachdonic, 5,8,11,14,17-eicosapentaenoic (EPA),4,7,10,13,16,19-docosahexaenoic (DHA); branched-chain fatty acids suchas tuberculostearic, phytomonic, mycolipenic, mycocerosic, phytanic,pristanic; and dicarboxylic acids such as oxalic, malonic, adipic,succinic, glutaric, pimelic, suberic, azelaic, sebacic, alkilitaconatessuch as chaetomellic and ceriporic. Other fatty acids and variousderivatives include mono-, di- and triglycerides, polyglycerol esters,alkyl alcohol esters, aromatic alcohol esters, phenol esters, amides,amino acids, hydroxyacids, fatty acid salts, phospholipids, bile acidssuch as cholic, and chenodeoxycholic.

Various commercially available materials include fatty acids andderivatives derived from animal and vegetable sources. Some examples arelisted as follows: Animal fatty acid (distilled Tallow F.A.);Caprylic/capric acid blend; Caproic acid; Caprylic acid; Distilledcoconut fatty acid; Coconut Fatty Acid; Distilled mixed fatty acid;Distilled palm fatty acid; Distilled rice bran fatty acid; Distilledsoya bean fatty acid; Lauric acid; Myristic acid; Norfox oleic acid;Oleic acid; Olive oleic acid 75; Palmitic acid; Soap fatty acid;Specially formulated distilled coco F.A.; Specially formulated distilledtallow F.A.; Stearic acid; Vegetable stearic acid; Tall oil fatty acidsubstitute; Tall Oil Fatty Acids; Tallow fatty acid; Uniquema fattyacids; Butyl oleate; Butyl stearate; Calcium stearate; Cetostearylalcohol; Cetyl alcohol; Cetyl palmitate; Decyl oleate; Diacetin; Ethyllinoleate; Ethyl oleate; Ethyleneglycol distearate; Ethyleneglycolmonostearate; Ethylhexanoic acid; 2-Ethylhexyl cocoate; 2-Ethylhexyloleate; 2-Ethylhexyl palmitate; 2-Ethylhexyl stearate; 2-Ethylhexyltallowate; Glyceryl monococoate; Glyceryl monolaurate; Glycerylmonooleate; Glyceryl monostearate; Glyceryl tricaprylate/caprate,Glyceryl trioleate; 12-Hydroxystearic acid; Isobutyl oleate; Isobutylstearate; Isopropyl myristate; Isopropyl oleate; Isopropyl palmitate;Isostearyl isostearate; Isotridecyl stearate; Lauric acid; Linseed fattyacids; Linseed oil methyl ester; Magnesium stearate; Methyl cocoate;Methyl laurate; Methyl oleate; Methyl ricinoleate; Methyl stearate;Methyl tallate; Methyl tallowate; Myristic acid; Neopentylglycoldioleate; Octyl cocoate; Octyl oleate; Octyl palmitate; Octyl stearate;Octyl tallowate; Octyldodecanol; Oleic acid; Oleyl alcohol; Oleylerucate; Oleyl oleate; Palmitic acid; Pelargonic acid; Pentaerythritoltetraoleate; Propyleneglycol; caprylate/caprate; Propyleneglycoldioleate; Propyleneglycol dipelargonate; Propyleneglycol monostearate;Propyleneglycol ricinoleate; Rapeseed methyl ester; Ricinoleic acid;Sorbitan monolaurate; Sorbitan monooleate; Sorbitan monopalmitate;Sorbitan monostearate; Sorbitan trioleate; and Sorbitan tristearate.

Below in Table 1 is a listing of fatty acid containing compounds usefulin the practice of this invention.

TABLE 1 Common name acid Structure Source Acetic 2:0 Platelet activatingfactor Acrylic 2e-3:1 Nnc Adipic 6:0 di-acid Nnc Adrenic7c10c13c16c-22:4 Adrenal lipids Agonandoic (aka. ximenynic) 9a,11t-18:2Santalum acuminatum Agonandric 8-OH 9a11t-18:2 Agonandra (Opiliaceae)Alchornoic cis-14, 15-ep 11c-20:1 Alchornia cordifolia Alepramic 3-Cp3:0 Flacourtiaceae seed oils Aleprestic 5-Cp 5:0 Flacourtiaceae seedoils Alepric 9-Cp 9:0 Flacourtiaceae seed oils Aleprolic 1-Cp 1:0Flacourtiaceae seed oils Aleprylic 7-Cp 7:0 Flacourtiaceae seed oilsAleuritic 9,10,16-triOH 16:0 Shellac Ambrettolic 16-OH 7c-16:1 Muskmellon seed oil Angelic 2Me 2c-4:1 Angelica archangelicaAnteisoheptadecanoic 14Me 16:0 Animal fats Anteisononadecanoic 16Me 18:0Animal fats Anteisopentadecanoic 12Me 14:0 Animal fatsAnteisotridecanoic 10Me 12:0 Animal fats Arachidic 20:0 Groundnut(peanut) oil Arachidonic 5c8c11c14c-20:4 Animal phospholipids Argenonic6-OH, 6-Me, 9-oxo-28:0 Papaveraceae Artemesic See Coriolic — Asclepic11c-18:1 Asclepia oils Ascorbic Vitamin C — Auricolic 14-OH 11c17c-20:2Lesquerella auriculata Avenoleic 15(R)-OH 9c12c-18:2 Axillarenic11,13-di OH, 9c-24:1 Euphorbiaeceae Azelaic 9:0 di-acid Nnc Behenic 22:0Lophira alata Behenolic 13a-22:0 Nnc Bishomopinolenic 7c,11c,14c-20:3Bolekic 9a11a13c-18:3 Isano oil Bosseopentaenoic 5c8c10t12t14c-20:5Bossiella orbigniana Brassidic 13t-22:1 Trans form of erucic acidBrassylic 13:0 di-acid Nnc Buiolic (jalapinolic) 11-OH 16:0 Butolic 6-OH14:0 Shellac Butyric 4:0 Milk fats Calendic (α) 8t10t12c-18:3 Calendulaofficinalis Calendic (β) 8t10t12t-18:3 Trans form of α-calendic acidCapric 10:0 Lauric oils Caproic 6:0 Milk fats Caproleic 9c-10:1 Milkfats Caprylic_(—) 8:0 Lauric oils Carboceric 27:0 — Catalpic9t11t13c-18:3_(—) Catalpa ovata Cerebronic 2-OH 24:0 CerebrosidesCerinic See Cerotic — Ceromelissic 33:0 (see psyllic) — Ceroplastic 35:0Nnc Cerotic 26:0 Waxes Cervonic DHA — Cetelaidic 11t-20:1 Hydrogenatedfish oils Cetoleic 11c-22:1 Fish oils Chaulmoogric 13-Cp 13:0Flacourtiaceae seed oils Chrysobalanic 4-oxo 9c11t13t15c-18:4Chyrsobalanus icaco Civetic 8t-17:1 di-acid CLA Conjugated 18:2 Ruminantfats isomers Clupadonic 7c10c13c16c19c-22:5 Fish oils Colneleic9-oxa-8t10t12c-18:3 Enzymic oxidation of linoleic acid Colnelenic9-oxa-8t10t12c15c-18:4 Enzymic oxidation of linolenic acid Columbinic5t9c12c-18:3 Aquilegia vulgaris Coniferonic 5c,9c,12c,15c-18:4 ConiferConvolvulinolic 11-OH 14:0 Ipomea oils Coriolic 13-OH 9c11t-18:2Xeranthemum annuum Coronaric Cis-9,10-ep 12c-18:1 Chrysanthemumcoronarium Couepic See Licanic — Couepinic (licanic?) 4-keto9c11c13c-18:3; — Crepenynic 9c12a-18:2 Crepis and Afzelia oils DaturicSee Margaric Animal fats Dehydrocrepenyic 9c12a14c-18:3 —Demospongic_(—) C24–C34 5c9c-diene Sponges acids Densipolic 12(R)-OH9c15c-18:2 Lesquerella densipila DHA 4c7c10c13c16c19c-22:6 Fish oils*Dicramin 9c12c15c6a-18:4 dicramium scoparium Dihomolinoleic 11c14c-20:2Dihomolinolenic 8c11c14c-20:3 Animal fats Dihomo Mead's acid7c10c13c-22:3 Dihomopinolenic 7c11c14c-20:3 Pinacae familyDihomotaxoleic 7c11c-20:2 Taxus spp. Dihydroxystearic 9,10-diOH 18:0 —*Dimorphecolic 9-OH, 10t, 12t-18:2 Dimorphecolic pluvialis DPA7c10c13c16c19c-22:5 Fish oils Elaidic 9t-18:1 Trans isomer of oleic acidElaidolinolenic See Linolenelaidic — EPA 5c8c11c14c17c-20:5 Fish oilsEleostearic (α) 9c11t13t-18:3 Tung oil Eleostearic (α) 9c11t13t-18:3Momordica charantia** Eleostearic (β) 9t11t13t-18:3 All-transα-eleostearic acid Enanthic 7:0 Nnc Ephedrenic 5c,11c-18:2 EphedraErucic 13c-22:1 Cruciferae seed oils Erythrogenic See Isanic — Exocarpic9a11a13t-18:3 Isano oil Gadelaidic 9t-20:1 Trans form of gadoleic acidGadoleic 9c-20:1 Fish oils Gaidic 2t-16:1 — Geddic 34:0 — Gheddic 34:0 —GLA 6c9c12c-18:3 Evening primrose, borage, etc Glutaric 5:0 di-acid NncGondoic 11c-20:1 Fish oils *Gondoleic 9c-20:1 — Gorlic 13-Cp 6c-13:1Flacourticeae oils Helenynolic 9-OH 10t12a-18:2 Helychrysum bracteatum*Hiragonic 7c10c13c-16:3 Fish oils Hormelic 15-Cp 15:0 Flacourticeaeoils Hydnocarpic 11-Cp 11:0 Flacourticeae oils *Hydrosorbic 3e-16:1di-acid — Hydroxycerebronic 2-hydroxycerebronic SphingolipidsHydroxynervonic 2-hydroxynervonic Sphingolipids Ipurolic 3,11-diOH 14:0Ipomoca oils Isanic 9a11a17e-18:3 Isano oil Isanolic 8-OH 9a11a17e-18:3Isano oil Isoarachidic 18-Me 19:0 — Isobutyric 2-Me 3:0 — Isocaproic4-Me 5:0 — Isocerotic 24-Me 25:0 — Isoheptadecanoic 15-Me-16:0 —Isolauric 10-Me-11:0 — Isomargaric 15-Me 16:0 — Isomontanic 26-Me-27:0 —*Isomycomycin 3c5c7a9a11a-13:5 — Isomyristic 12-Me 13:0 —Isononadecanoic 17-Me 18:0 — Isopalmitic 14-Me 15:0 — Isopentadecanoic13-Me 14:0 — Isoricinoleic 9-OH, 12c-18:1 Strophanthus Isostearic16-Me-17:0 — Isotridecanoic 11-Me 12:0 — *Isovaleric 3-Me 4:0 Porpoise,dolphin Jacaric 8c10t12c-18:3 Jacaranda mimosifolia Jalapinolic 11-OH16:0 Jalap resin Japanic 21:0 di-acid — Jasmonic C12 cyclopentaneacid_(—) Linoleic acid metabolite Juniperic 16-OH 16:0 Conifer waxesJuniperinic 16-OH 16:0 Conifer waxes Juniperonic 5c11c14c17c-20:4Conifer waxes Kamlolenic (α) 18-OH 9c11t13t-18:3 Kamala oil *Kamlolenic(β) 18-OH 9t11t13t-18:3 Kamala oil *Kerrolic 4-OH-16:0 ShellacKeteleeronic 5c11c-20:2 Gymnosperm sp Labellenic 5,6-18:2 (R)-formLeonotis seed oil Lacceric 32:0 Stick lac wax Lacceroic See laccericStick lac wax Lactarinic 6-oxo 18:0 Lactarius rufus Lanoceric di-OH 30:0— Lamenallenic 5,6,16t-18:3 Laminium purpureum Lactobacillic 11,12-Mt18:0 Micro-organisms Lauric 12:0 Lauric oils Lauroleic 9c-12:1 —Lesquerolic 14-OH 11c-20:1 Lesquerella spp Levulinic (aka levulic)4-oxo-5:0 Licanic (α) 4-oxo 9c11t13t-18:3 Licania rigida Licanic (β)4-oxo 9t11t13t-18:3 Trans-form of α-licanic acid Lignoceric 24:0 WaxesLinelaidic 9t12t-18:2 All-trans form of linoleic acid Linderic 4c-12:1Lindera obtusiloba Linoleic_(—) 9c12c-18:2 All seed oils Linolenelaidic9t12t15t-18:3 All-trans form of linolenic acid_(—) Linolenic_(—)9c12c15c-18:3 Linseed Lumequic 21c-30:1 Ximenia spp Linusic9,10,12,13,15,16-OH From linolenic acid 18:0 Malonic 3:0 di-acid_(—) —Malvalic 8,9-Mt 8c-17:1 Cottonseed oil Manaoic 11-Cp 6c-11:0Flacourtiaceae seed oils Mangold's acid 9t11t-18:2 — Margaric 17:0Animal fats Margarolic 9c-17:1 Mead's acid 5c8c11c-20:3 Metabolite ofoleic acid_(—) Megatomic 3t5c-14:2 Black carpet beetle pheromoneMelissic 30:0 Bayberry Mikusch's acid 10t12t-18:2 — Montanic 28:0 Waxes(ie. carnuba) Moroctic See stearidonic — Morotic See stearidonic —Mycoceranic 2,4,6-triMe 26:0 Tubercle bacilli Mycocerosic Seemycoceranic — Mycolic RCHOHCH(R')COOH Mycobacteria Mycolipenic2,4,6-tri-Me-2t-24:1 tuburele bacilli Mycomycin 3t5c7,8,10a12a-13:6 —Myristelaidic 9t-14:1 Trans form of myristoleic acid Myristic 14:0Lauric oils Myristoleic 9c-14:1 — Nemotinic 4e6a8a10a-11:4 —*Nemotinic_(—) 4-OH, 5,6,8a,10a-11:4 Basidomycetis moulds Nervonic15c-24:1 Honesty seed oil, nerve tissue Nisinic 6c9c12c15c18c21c-24:6Fish oils Obtusilic 4c-14:1 Lindera obtisiloba Oleic 9c-18:1 All oilsand fats Oncobic 15-Cp 8c-15:0 Flacourtiaceae seed oils Osband's acidSee DPA — Oxalic 2:0 di-acid — Paullinic cis-13-eicosenoic acidPalmitelaidic 9t-16:1 Trans form of palmitoleic acid_(—) Palmitic 16:0All oils and fats Palmitoleic 9c-16:1 Fish oils, macadamia oil Parinaric(α) 9c11t13t15c-18:4 Parinarium laurinum Parinaric (β) 9t11t13t15t-18:4Trans-form of α-parlnaric acid Pelargonic 9:0 — Petroselaidic 6t-18:1Trans form of petroselinic acid_(—) Petroselinic 6c-18:1 Umbelliferaeoils Phellonic 22-OH 22:0 Cork Phloionolic 9S10S18S-triOH 18:0 CorkPhlomic 7,8-20:2 *Phthioic 3,13,19-triMe 23:0 — Phrenosic See cerebronic— Phrenosinic See cerebronic — Phthianoic See mycoceranic — PhthioicPolybranched acids Micro-organisms Physeteric 5c-14:1 Whale oilPhysetoleic See Palmitoleic — Phytanic_(—) 3,7,11,15-tetraMe 16:0 Marineanimal fats *Phytenic See Phytenoic — Phytenoic 3,7,11,15-tetraMe 2e-Marine animal fats 16:1 Phytomonic See Lactobacillic — Pimelic_(—) 7:0di-acid — Pinolenic 5c9c12c-18:3 Toucrium depressum Podocarpic5c11c14c-20:3 Podocarpus nagera Pristanic 2,6,10,14-tetraMe 15:0 Marineanimal fats Pseudoeleostearic 10t12t14t-18:3 Isomerized linolenicacid_(—) Psyllic 33:0 — Punicic 9c11t13c-18:3 Punica granatum Punicic9c11t13c-18:3 Trichosanthes anguina* Pyrulic 8a10t-17:2 Pyrularia puberaRicinelaidic 12-OH 9t-18:1 Trans form of ricinoleic acid_(—) Ricinoleic12-OH 9c-18:1 Castor oil Rosilic 10-OH 18:0 Leaf waxes Rumenic9c11t-18:2 Ruminant fats Sabinic 12-OH 12:0 Juniperus oxycedrus leavesSantalbic See ximenynic — Sativic 9,10,12,13-tetraOH 18:0 From oxidationof linoleic acid_(—) Sciadonic 5c11c14c-20:3 Pinus species *Scoliodonic24:5_(—) — Sebacic 10:0 di-acid — Selacholeic 15c-24:1 (see nervonic)Shark liver oils Shibic 26:5 Fish oils *Sorbic 2t4t-6:2 di-acid —Stearic 18:0 Animal fats, cocoa butter Stearidonic 6c9c12c15c-18:4Echium oils, fish oils Stearolic 9a-18:1 Santalaceae Sterculic 9,10-Mt9c-18:1 Cottonseed oil Sterculynic 9,10-Mt 9c17a-18:2 Sterculia alataStillingic 2c4t-10:2 Sepium sebiferum Strophanthus 9-OH,12c-18:1Apocyanaceae Suberic 8:0 di-acid_(—) — Succinic 4:0 di-acid — Tariric6a-18:1 Picramnia spp Taxoleic 5c9c-18:2 Gymnospermae seed lipidsThapsic (or thaspic) 16:0 di-acid Waxes Thynnic 26:6 (probably n-3) Fishoils Timnodonic (see EPA) 4c8c12c15c18c-20:5c** — Traumatic 2t-20:1di-acid — Trichosanic See punicic — Tsuduic 4-14:1 Lindera obtisilobaTsuzuic 4-14:1 Lindera obtisiloba Tuberculostearic 10-Me 18:0 Tuberclebacilli Undecylenic 10e-11:1 Castor oil Ustilic 15,16-diOH 16:0Ustilagic acid (antibiotic) Vaccenic 11t-18:1 Ruminant fats Valeric 5:0— Vernolic 12,13-ep, 9c-18:1 Vernonia oils Wyerone acid2c,(3,4-F*),5a7c-10:3 Exocarpus cupressiformis Ximenic 17c-26:1 Ximeniaamericana Ximenynic 9a11t-18:2 Santalum acuminatum Ximenynolic 8-OH,9a11t-18:2 Zoomaric See palmitoleic — c = cis, t = trans, a = acetylenee = ethylenic bond (stereochemistry not relevant or unknown) ep = epoxyMe = methyl group Mt = methano —CH₂— Cp = 2-cyclopentenyl (C5H7) P =cyclopropenyl Nnc = not natural constituent of normal fats. F* =furanoid *= Spelling or structure uncertain. **= Original designation ofstructure incorrect; more probable structure listed. Examples: 14:2 = 14carbon atoms, 2 sites of unsaturation. 9:0 di-acid = HOOC(CH2)7COOHReferences cited within Table 1 include the following: 1) C. Y. Hopkins(1972), Fatty Acids with Conjugated Unsaturation, in Topics in LipidChemistry (F. Gunstone, ed.), Elek Science, London, pp. 37-87; 2) P. G.Robinson (1982), Common Names And Abbreviated Formula For Fatty Acids.J. Lip. Res. 23:1251-1253; 3) G. D. Fasman (1989), Practical Handbook ofBiochemistry and Molecular Biology, CRC Press, Boca Raton, Fla., pp.514-522; 4) F. D. Gunstone, J. L. Harwood and F. B. Padley, The LipidHandbook (2nd Ed.), Chapman and Hall, London, 1992; and 5) F. D.Gunstone and B. G. Herslof, A Lipid Glossary, The Oily Press, Dundee,first edition 1992, second edition in press.

Hydrophobic Fibers with Dimensional Stability in Wet State

In some applications it is advantageous that the cellulosic fibers beboth hydrophobic and not swell excessively in contact with aqueousfluids. This is important in situations in which the final productcontaining the hydrophobic fibers should have dimensional stability bothin dry and wet environment. Improved dimensional stability in wetconditions can be achieved for example by reducing the swelling of thefibers when in contact with moisture. The property of the swelling ofthe fibers can be measured indirectly by the analysis of their WaterRetention Value (WRV). The procedure for measuring WRV is describedbelow in Example 42. A decrease of the WRV of the fibers indicates areduction in the degree of swelling. According to the invention, onepossible way of achieving both hydrophobicity and reduced swelling ofthe cellulosic fibers is by imparting the hydrophobicity to them byusing various methods described in this invention and combining thistreatment with cross-lining of the fibers with or without additionalcross-linking agents. The cross-linking process can be carried out atvarious stages of the treatment of the cellulosic fibers. For example itcan be applied before the hydrophobic treatment, simultaneously with thehydrophobic treatment or after the hydrophobic treatment. Thecross-linking can also be initiated before the hydrophobic treatment andcarried out through the hydrophobic treatment process or can proceedduring the hydrophobic treatment stage and continue after thehydrophobic treatment has been completed.

Various known cross-linking agents can be used to effectively cross-linkcellulosic fibers. For example the use of formaldehyde and variousformaldehyde addition products to cross-link cellulosic fibers is knownin the art. This approach is described in U.S. Pat. No. 3,224,926 (toBemardin); U.S. Pat. No. 3,241,553 (to Steiger); U.S. Pat. No. 3,932,209(to Chatterjee); U.S. Pat. No. 4,035,147 (to Sangenis et al.); and U.S.Pat. No. 3,756,913 (to Wodka). Other references disclose the use ofdialdehyde cross-linking agents. See, for example, U.S. Pat. No.4,689,118 (to Makoui et al.) and U.S. Pat. No. 4,822,453 (to Dean etal.). Dean et al. discloses absorbent structures containingindividualized, cross-linked fibers, wherein the cross-linking agent isselected from the group consisting of C₂-C₉ dialdehydes, withglutaraldehyde being preferred. The use of specific polycarboxylic acidsto cross-link cellulosic fibers is also known in the art. See, forexample, U.S. Pat. No. 5,137,537 (to Herron et al.), U.S. Pat. No.5,183,707 (to Herron et al.), and U.S. Pat. No. 5,190,563 (to Herron etal.). The Herron et al. patents disclose absorbent structures containingindividualized cellulosic fibers cross-linked with a C₂-C₉polycarboxylic acid. The ester cross-link bonds formed by thepolycarboxylic acid cross-linking agents are different from thecross-link bonds that result from the mono- and di-aldehydecross-linking agents, which form acetal cross-linked bonds.

Usually the cross-linking of cellulosic fibers requires a certain amountof energy to be delivered to them in order to accomplish thecross-linking process. This energy can be delivered to the fibers invarious forms such as, for example, in the form of heat treatment usingvarious known sources of thermal radiation. For example, applyingmechanical pressure to the fibers can also enhance the cross-linkingeffect. If thermal energy is used, the cross-linking of the fibers canoccur even without using additional chemical cross-linking agents. Thisis probably due to the self-cross-linking reactions, which can undergowithin the cellulosic fibers between the functional groups of cellulose.To enhance the effect of the self-cross-linking of cellulose suchreactions can be catalyzed by various catalysts such as metal salts,oxides and other metal-containing compounds.

According to the invention, the swelling of cellulosic fibers in wetconditions can also be reduced for instance by imparting hydrophobicityboth to the surface of the fibers and to the inside of the fibers. Thiscan be accomplished, for example, by pre-swelling the cellulosic fibersbefore the hydrophobic treatment in order to facilitate the penetrationof the hydrophobic agents inside the fiber. As a result, the obtained,dried fibers become hydrophobic both on the surface and on the inside.This makes them more resistant to swelling in moist conditions thusimparting greater dimensional stability. The pre-swelling of the fibersis possible by using various swelling agents known to effectively swellcellulose. An example of such known treatment is swelling of cellulosein aqueous solution of sodium hydroxide. In this case, the pre-swollencellulosic fibers can be treated subsequently with a hydrophobic agentto impart hydrophobicity to them. For instance, it can be done bytreating the pre-swollen fibers with a polyvalent metal salt toprecipitate the polyvalent metal hydroxide within the fibers and on thesurface of the fibers and then by applying a soluble salt of fatty acidto the fibers. Without being bound to theory, it is believed that as aresult of such a treatment, an insoluble, hydrophobic salt of thepolyvalent metal and the fatty acid is formed within and on the surfaceof the fibers. Various cellulose swelling agents are known and can beused in the present invention.

Treatment of Cellulosic Fibers with Hydrophobic Agents

Another aspect of the invention is hydrophobic cellulosic fibers and amethod of imparting hydrophobicity to them by treating the fibersdirectly with a hydrophobic agent such as a fatty acid or a polyvalentmetal salt of a fatty acid at a temperature close or above the meltingpoint of the hydrophobic agent. An example of the hydrophobic agent usedin the invention would be aluminum stearate. This compound melts at atemperature of about 110—about 115° C. and can form a coating on thecellulosic fibers thus rendering them hydrophobic.

Yet another aspect of the present invention is hydrophobic cellulosicfibers and a method of imparting hydrophobicity to them by treating thefibers directly with a solution of a water-insoluble hydrophobic agentin a suitable solvent such as various organic solvents.

A hydrophobic agent used for treating the cellulosic fibers can be usedas a component of carrier in the form of particles such as other fibers,for example synthetic fibers, which can be blended with the cellulosicfibers and the blend is then cured at a temperature allowing thehydrophobic agent to melt or change into vapor. Without being bound totheory it is believed that the hydrophobic agent in the form of a liquidor vapor can diffuse out of the carrier particles and coat thecellulosic fibers thus rendering them hydrophobic.

When used in the preparation of fibers bound with a polyvalentcation-containing compound and coated thereon a fatty acid containingcompound, the fatty acid containing compound desirably is applied in anamount of from about 0.01 part fatty acid containing compound to about 5parts fatty acid containing compound per 100 parts of treated fiber,which is from about 0.01 weight percent to about 5 weight percent, basedon the weight of the treated fiber, more desirably, the fatty acidcontaining compound is from about 0.01 weight percent to about 3 weightpercent, preferably from about 0.05 weight percent to about 1.5 weightpercent, more preferably from about 0.1 weight percent to about 1 weightpercent.

The fatty acid containing compound may be applied to the fibers invarious ways, such as, for example, by spraying the compound which maybe heated to increase fluidity, or as a solution or suspension in aliquid, such as water or an organic liquid, or as an aqueous solution ofa soluble salt of the fatty acid, such as, for example, an alkali metalsalt, preferably a sodium salt.

The addition of filler to the material of the present inventionincreases barrier performance by partially blocking the pores of thenonwoven web, resulting in improved barrier quality. Filler suitable foruse in the practice of this invention include calcium carbonate, variouskinds of clay, such as, for example, bentonite and kaolin, silica,alumina, barium sulfate, sodium carbonate, talc, magnesium sulfate,titanium dioxide, zeolites, aluminum sulfate, cellulose-type powders,diatomaceous earth, magnesium sulfate, magnesium carbonate, bariumcarbonate, mica, carbon, calcium oxide, magnesium oxide, aluminumhydroxide, pulp powder, wood powder, cellulose derivative, polymerparticles, chitin and chitin derivatives.

In one embodiment of this invention, a solid material capable of formingphysical and/or chemical bonds with a polyvalent metal containingcompound is treated in the first step with polyvalent metal-containingcompound, and in the second step with a fatty acid containing compoundto produce a hydrophobic coating on the solid material. This isaccomplished by treating the solid material with a polyvalentmetal-containing compound to attach the polyvalent metal to the solidmaterial and then by depositing on it a fatty acid containing compoundwhich is capable of forming ionic an/or coordination bonds with thepolyvalent metal.

These two steps can be conducted separately or in a continuous process.The polyvalent metal containing compound can be deposited on the solidmaterial, for example, by spraying in the form of a microdispersion, orby dipping the solid material in a solution or dispersion of thepolyvalent metal-containing compound. The polyvalent metal containingcompound is deposited on the solid material in its insoluble form andhas a general formula of MeA, where Me is the polyvalent metal cationand A is an anionic group. The polyvalent metal can form a physical bondwith the solid material or be fixed on the surface through chemicalbonds. The fatty acid containing compound can be in the form of a liquidor gaseous microdispersion containing the fatty acid containingcompound. The fatty acid containing compound can be used either in aliquid form or in a vapor form.

In the method of the invention, the fatty acid containing compoundproduces a compound having a general formula of RCOOB, where R is anorganic, generally hydrophobic group and COOB is a carboxyl group COOH,where B is a hydrogen atom H, or COOB is a carboxylate group, where B isa monovalent metal. The COOB group is capable of reacting with the MeAcompound deposited on the solid surface to yield an insoluble product ofthe reaction between RCOOB and MeA.

As a result of this reaction, a byproduct BA is formed which can remainon the solid surface or can be removed by washing or by evaporation. Ineither case, to complete the reaction, after depositing the fatty acidcontaining compound on the solid material pretreated with the polyvalentmetal containing compound, a gas stream may be applied onto the solidmaterial. In the preferred embodiment, A in the MeA compound is ahydroxyl group OH and B in the RCOOB compound is hydrogen H. Then thebyproduct of the reaction between MeA and RCOOB is water, which iseasily removed by evaporation when applying the gas stream. The gasstream can also facilitate removal of any other volatile compounds suchas solvents used in the method of the invention. The scope of theinvention includes the hydrophobic solid material obtained, and can beused to obtain natural or artificial fibrous or inorganic materialsimpermeable to water and to aqueous solutions, and/or absorbing fats orboth hydrophobic and lipophobic materials.

The invention provides a solid material which is hydrophobic orlipophilic or both hydrophobic and lipophobic as well as a simple, rapidand low-cost treatment method which can be exploited in practice on theindustrial scale.

An object of the invention is to provide a treatment method of which theyield and kinetics are suitable for industrial scale. Another object ofthe invention is to provide a method which eliminates the use andcreation of toxic and corrosive reagents, effluents and residues.

One aspect of the invention provides a treatment method applicable tovarious solid materials, and, in general, any solid material capable ofcreating bonds with polyvalent metal containing compounds. Anotheraspect of the invention enables various materials to be treated, such ascellulose and other materials, including natural and synthetic organicpolymers in the form of fibers, paper, nonwovens and textiles, as wellas inorganic materials, such as glass. Suitable polymers include forexample polyamides such as nylon 6 or nylon 66, polyesters such aspoly(ethylene terephthalate), poly(oxyethylene), poly(vinyl alcohol),chitosan, chitin, starch, and collagen.

The invention concerns a method for treating a solid material to deposita polyvalent metal ion containing compound MeA on the solid material. Inone embodiment the MeA reacts with reactive functional groups of thesolid material to form a physical and/or chemical bond such as acovalent, coordination and/or ionic bond. Thus, the polyvalent metalcation is bound to the surface of the solid material. In the second stepa bond is created between the polyvalent metal ion containing compoundand fatty acid containing compound, wherein a fatty acid containingcompound ROOB is used, where B is hydrogen H or monovalent metal and Ris an organic, generally hydrophobic group, ROOB being selected so thatit can react with the polyvalent metal containing compound MeA depositedon the solid material, to produce a chemical bond, generallycoordination and/or ionic bond, with ROOB with formation of a byproductin the form of the BA salt or water, where the latter can be evaporatedunder the reaction conditions. A liquid or gaseous microdispersion isproduced of a composition containing a fatty acid containing compoundand applied on the solid material with deposited MeA, and a gas stream,which is neutral to the reaction of ROOB with MeA deposited on the solidmaterial, is applied to facilitate the distribution and diffusion ofROOB to the parts of the solid material with deposited MeA accessible tothe gas stream and to facilitate the removal of any volatile byproducts.

The solid material may contain reactive functional groups, which enablethe formation of physical and/or a chemical bonds with the polyvalentmetal containing compound. If the solid material is a structure composedof fibers such as cellulosic fibers then the first stage of thetreatment may be accomplished by treating the fibers with a polyvalentmetal containing compound and then making the structure constituting thesolid material. Thus, the solid material produced will contain on itssurface a polyvalent metal containing compound.

As used herein, the term “microdispersion” means a dispersion of liquiddroplets having a mean diameter equal to or less than 1×10⁻⁶ meter (1micron). A microdispersion according to the invention may be produced onat least part of at least one first free outer face of the solidmaterial simply by contacting the material with the microdispersion, forexample, either by spraying directed onto this first free outer face ofthe solid material, or by application of a solid support loaded with theliquid composition in contact with this first face, or by wetting, forexample, by immersion in a bath of the liquid composition containing avolatile solvent, followed by evaporation of this volatile solvent.

A quantity of liquid composition containing fatty acid containingcompound is applied in contact with at least one first free outer faceof the solid material. A gas stream is then applied to at least one freeouter face of the solid material, which may be the same first face oranother face. The microdispersion is preferably deposited on the solidmaterial before applying the gas stream to the solid material.Alternatively, the gas stream can also be applied to the solid materialat the same time as a microdispersion is deposited thereon. In thiscase, care should be taken to prevent vaporization of the liquidcomposition before it comes into contact with the solid material.

In a preferred method, a microdispersion of at least one liquidcomposition including a fatty acid containing compound is deposited byspraying directed towards the solid material, for example, with a nozzledirected towards one face of the solid material. Alternatively,deposition can be accomplished by contact of the material with a solidsupport previously loaded with a liquid composition mainly consisting ofa fatty acid containing compound in the liquid state and/or by wettingthe solid material with a liquid composition formed of a solution of thefatty acid containing compound in a neutral volatile solvent. The solidsupport loaded with liquid composition may be chosen from an absorbentpad applied to the solid material, for example, a pad of the felt type,a non-absorbent pad, for example of the dating pad type, an absorbent ornon-absorbent roller driven in rotation by rolling on the first face ofthe solid material, for example, of a paint roller or printing machineinking cylinder type, or a brush or the equivalent.

In order to wet the solid material, it may be immersed in a bath of theliquid composition. As soon as it leaves the bath, the neutral volatilesolvent evaporates, leaving in place microdroplets of the fatty acidcontaining compound dispersed on the solid material.

The liquid composition may also incorporate a solvent, in particular, avolatile neutral solvent. If a fatty acid containing compound is solublein polar solvents such as in the case of a fatty acid salt of amonovalent metal, the volatile solvent is for example water or thesolvent is chosen from the group formed of polar organic solvents suchas water, alcohols, ketones, etc. On the other hand, if a fatty acidcontaining compound is soluble in nonpolar solvents as in the case of along-chain fatty acid in its neutral form, then the volatile solvent canbe chosen for example from the group formed of petroleum ethers, lowmolecular weight alkyl esters, such as ethyl acetate, or chlorinatedsolvents such as chloroform, trichloroethylene, etc. If a fatty acidcontaining compound is a liquid, it may not be necessary to use asolvent.

The gas stream is applied continuously and a gas flow coming from thesolid material is evacuated so as to prevent any recirculation onto thesolid material. The gas flow coming continuously from the solid materialmakes it possible in particular to evacuate continuously the volatilecompounds. For example, when the fatty acid containing compound is afatty acid in its neutral form and the polyvalent metal containingcompound is a hydroxide of the polyvalent metal, the volatile byproductof the reaction is water.

In one embodiment of the invention, the stream of gas is directedtowards the surface of the solid material with a positive velocitycomponent perpendicular to the surface of the solid material.

It should be noted in particular that, unlike former vapor phasetreatment methods involving the use of fatty acid chlorides as disclosedin U.S. Pat. No. 6,342,268, in the method of this invention, both thereagents and the by products are neutral, non-toxic and non-corrosive.

A function of the gas stream applied to the solid material has thefunction of bringing about entrainment of the fatty acid containingcompound initially placed in microdispersed form in the liquid state onthe solid material on sites occupied with the polyvalent metalcontaining compound, and of removing any excess. It has the function ofenabling the reaction between the polyvalent metal containing compoundand the fatty acid containing compound to take place of entraining anyvolatile byproducts formed by the reaction. It has the function ofdriving the kinetics of the reaction forward by removing volatilebyproducts.

As an example, a reaction between a solid material having on its surfacepolyvalent metal containing compound attached in the form of polyvalentmetal hydroxide MeOH and a fatty acid RCOOH, may be written according tothe following equation (I):

where K₁ and K₂ are velocity constants in the direction of formation anddissociation respectively. The rate of reaction may be written accordingto the following equation (II):V═K₁[(Material)-MeOH][RCOOH]—K₂[(Material)-Me—OOCR][H₂O]  (II).

R is, for example, an organic group containing more than 6 carbons, inparticular between 8 and 50 carbons, is in general hydrophobic. R may bechosen from the family of aliphatic or aromatic radicals derived fromfatty acids containing more than 10 carbons and in particular between 14and 50 carbons. R may or may not contain one or more hetero-atoms, andmay be saturated or unsaturated. For example, R may be a perfluorinatedalkyl group, the hydrophobic character of which is much more marked thanthe perhydrogenated alkyl group of the same carbon skeleton. R may alsoincorporate functions such as hydroxyl, amine or amide functions makingit possible to attach the fatty acid containing compound to polyvalentmetal containing compound deposited on the solid material in the firststage of the treatment. R can be from any of the previously named fattyacids, without the carboxyl group, of course. Examples of some verydesirable fatty acids are hydroxy acids, such as, for example, glycolic,lactic, malic, citric, tartaric, hyaluronic, alginic, salicylic,2-hydroxylinoleic, cerebranic, hydroxynervonic, 10-hydroxydecanoic,hydroxyallenic, ricinoleic, lesquerolic, densipolic, auricolic,beta-dimorphecolic; sulphur-containing acids dodeca thia acetic,tetradeca thia acetic; methoxy acids, such as, for example,2-methoxy-5-hexadecanoic, methoxytetradecanoic, methoxypentadecanoic,methoxyoctadecanoic; keto acids, such as, for example, 9-keto-decanoic;amino acids, such as, for example, alanine, beta-alanine arginine,asparagine aspartic acid, camitine, citrulline, cysteine, cystine,gamma-aminobutyric acid, glutamic acid, glutamine, glutathione, glycine,histidine, hydroxyproline, isoleucine, leucine, lysine, methionine,ornithine, phenylalanine, proline, serine, taurine, threonine,tryptophan, tyrosine, valine; and halogenated acids, such as, forexample, p-chlorophenoxyisobutyric acid, perfluoro-n-decanoic acid,perfluoro-n-octanoic acid, and perflorooctane sulfonic acid.

The solid material desirably has reactive groups such as alcohol (—OH),amino (—NH₂) and mercapto (—SH), such as, for example, polyamides suchas nylon 6 or nylon 66, polyesters such as poly(ethylene terephthalate),poly(oxyethylene), poly(vinyl alcohol), chitosan, chitin, starch, andcollagen. The solid material is preferably a cellulosic material in theform of nonwoven, paper, film, textile, natural or artificial fibres,and wood, etc.

The solid material can be made also of glass or silica or other solidinorganic or organic material capable of forming physical or chemicalbonds with polyvalent metal containing compounds.

In a preferred embodiment of this invention, treatment according to theinvention makes it possible to obtain a solid hydrophobic material. Invarious alternatives it is possible to provide the solid material withother properties according to the characteristics of the groups R.Accordingly, it is possible to choose hydrophobic groups R which mayhave in addition other properties, in particular which may be oleophobicif the group R is a perfluorinated organic group, and which areprotectors against ultra violet rays and/or absorb ultraviolet rays,colored rays etc. Useful in the practice of this embodiment of thisinvention are acids with perfluorinated organic groups, such as, forexample, perfluoro-n-decanoic acid, perfluoro-n-octanoic acid,perflorooctane sulfonic acid; and acids with uv absorbing groups, suchas, for example, acids containing chromophore aromatic groups such assalicylic acid, aminobenzoic acid, carminic acid.

At the start, the reaction proceeds with a high velocity since there isno negative contribution from the second term of the expression. In aclosed system, this rate however may decrease with the increase inconcentration of (Material)-Me —OOCR and of H₂O. In an open system thereaction can be easily completed by removing H₂O, for example, byevaporation.

In one example of the prior art, the attachment of fatty acid acylgroups to the solid material was achieved in the vapor phase by usingfatty acid chlorides. Such compounds are sensitive to moisture, producestrong odor and are toxic. The byproduct of the reaction of fatty acidchlorides with the protogenic groups of the solid material is hydrogenchloride, which is very toxic and corrosive.

The solid material with attached polyvalent metal containing compound isplaced in a treatment space adapted so as to minimize, or even prevent,according to the characteristics of the gas stream, any return onto thesolid material of the gas flow coming from the solid material. If thesolid material is non-porous or only slightly porous, the treatmentspace should be sufficiently large in the transverse direction withrespect to the incident gas stream so that the gas flow can be evacuatedwithout being recirculated to the solid material. The side walls of thetreatment space surrounding the solid material must not come intocontact with the solid material in the transverse direction.

If it is perfectly porous, the solid material with attached polyvalentmetal containing compound may be placed in a treatment space which issmaller in the transverse direction, and of substantially the sametransverse size as the solid material. However, application of the gasstream and evacuation of the gas flow coming from the solid material isthen carried out in open circuit.

Whether the solid material is porous or non-porous, the solid materialwith attached polyvalent metal containing compound is placed in atreatment space adapted according to the characteristics of the gasstream so that the quantity of gas flow coming from the solid materialwhich can once again be brought onto the solid material by the gasstream is zero or negligible. Optionally, the solid material is placedin a ventilated oven or in an open atmosphere under an extraction hoodevacuating the gas flow to the outside. The treatment space is adaptedso that, if the treatment space is sufficiently large, the volatilesolvents are extracted by dilution from the solid material as it isformed, and/or is extracted by forced evacuation. Desirably, thetreatment space is not hermetically sealed but is open and may be putinto operation with fresh air in an open atmosphere. Gases useful in thepractice of this embodiment of the invention are inert under theconditions used and include, for example, air, nitrogen, helium, carbondioxide.

It is possible, in a variant of the operating method of the invention,to apply a gas stream and a stream of a microdispersion of fatty acidcontaining compound simultaneously in the form of a spray directed ontoat least one free outer face of the solid material. In this case, thegas stream contains the microdispersion of fatty acid in the liquidstate, and it is desirable that the temperature of the gas stream shouldbe as low as possible so as to prevent any vaporization of the fattyacid containing compound before arrival on the solid material. However,it is then advantageous to provide a subsequent step during which a gasstream free from the fatty acid containing compound is applied at ahigher temperature in order to encourage the treatment.

The method according to the invention may be carried out with ambientair and with a material which is not previously dried. The gas streammay thus be quite simply atmospheric air or dry air. It is also possibleto use any other neutral gas, for example pure nitrogen or carbondioxide, to prevent the oxidation of the material or of the reagent.

The physical characteristics of the gas stream velocity, flow rate,temperature, pressure, dimensions are adapted in relation to the solidmaterial to be treated and the operating conditions selected. Inparticular, a gas stream is chosen having a sufficiently low velocity sothat the dwell time of the fatty acid containing compound on thematerial at the chosen reaction temperature is sufficiently long toallow time to react with all the sites of the solid material withpolyvalent metal containing compound attached to it.

The gas stream may be formed by any appropriate means, for example withthe aid of one or more fans positioned so as to operate in compressionand/or in extraction.

In FIG. 8, a sample of solid material such as a glass plate, a piece ofpaper or other material, pretreated with polyvalent metal containingcompound, is placed under a rotating fan 2 directing a gas stream 3, forexample formed of atmospheric air at ambient temperature, onto a freeouter face 4 of the sample 1, on which a microdispersion 5 has alreadybeen formed of a liquid composition of a fatty acid containing compoundfor example by means of an absorbent pad impregnated with a liquidcomposition applied with pressure onto the face 4. The gas flow 6 comingfrom the sample 1 is formed of the reflected flow 6 a and the flow 6 bhaving passed through the sample 1 if the latter is porous. These flows6 a, 6 b are evacuated either to the open air as shown or into anextraction hood if the assembly is placed under a hood. If the sample 1is porous, it is treated throughout all its thickness. If it is notporous, only its face 4 is treated.

FIG. 9 illustrates a continuous method for producing a strip 9 of solidmaterial such as printing paper with attached polyvalent metalcontaining compound, in which a spray nozzle 10 is used to spray theliquid composition of a fatty acid containing compound onto the part 11of the free outer face 12 of the strip 9 which passes in the gas stream3 formed by the fan 2. Preferably, the spray nozzle 10 is inclinedcounter-currently to the direction of movement of the strip 9 under thefan 2.

As a variant, not shown, the nozzle 10 could also be placed upstream tothe gas stream 3 with respect to the direction of movement of the strip9. The treatment then comprises two successive stations: a sprayingstation followed by a station for applying the gas stream 3.

In the variant of FIG. 10, a blower 13 is used, which may be providedwith means for heating the gas stream 15. The sample 18 has beenpreviously wetted with a liquid composition of fatty acid containingcompound contained in a vessel 19 by simply soaking it instantaneouslyin the bath of the vessel 19. The sample 18 is placed under anextraction hood 20.

This variant may be used with a porous sample 18, which is then treatedthroughout its thickness. Several blowers 13 may be used to treat eachlarge face of the sample 18.

The variant of FIG. 10 may also be used with a non-porous sample, theliquid composition being formed of a highly diluted solution of fattyacid containing compound in a neutral volatile solvent evaporated by thegas stream, or before applying the gas stream, so as to leave only amicrodispersion on the surface.

The method according to the invention has many advantages compared withthe prior art, and in particular rapid reaction times make it possibleto work at relatively high temperatures and the material, polyvalentmetal containing compound and fatty acid containing compound are indeedonly subjected to these high temperatures for a very short time; noharmful reaction substrates such as fatty acid chlorides or byproducts,such as gaseous halogenated acids, are produced during the treatment;the reaction can take place without any solvent or catalyst, andgenerates products which do not present any safety or environmentalproblems; and the reaction may be carried out with many commercialreagents, which are for the greater part low in cost.

In general, the treated material does not require any washing orsubsequent treatment. The method is very simple and does not require theuse of strictly anhydrous conditions or an inert atmosphere, or aconfinement chamber, and in most cases, the ambient air may be used asthe carrier gas, and the solid material may be used without previousdrying. It is possible to treat large areas of solid material easily insitu, whether continuously or not. The invention may thus make itpossible to obtain a solid material containing on all its specific areaaccessible to the gases, and solely on this surface, hydrophobic groups,which can include between 8 and 50 carbons.

The invention applies in this respect to very many different solidmaterials. Accordingly, a solid material according to the invention maybe:

a solid material permeable to gases, the method according to theinvention not affecting the gas permeability property of the material;

a solid biodegradable material, the method according to the inventionnot affecting the biodegradability properties of the material;

a colored solid material, the method according to the invention notaffecting the color of the material;

a solid material essentially formed of crosslinked polymericmacromolecular material(s), when sufficient durability of thehydrophobic character is desired, or non-crosslinked polymericmacromolecular material(s), if durability is not desired or on the otherhand if low durability is desired;

a solid material essentially formed of cellulosic materials;

a solid material formed of a natural or artificial fibrous structurebeing in the form of a sheet or divided form in particular paper, awood-based structure, or a textile structure, impermeable to water andto aqueous solutions and/or absorbing fats; and

a solid material formed of a porous or non-porous inorganic structure,in particular glass or silica.

It should also be noted that the solid material according to theinvention may be porous or fibrous, but it is not necessarily porous orfibrous. In particular, the solid material according to the inventionmay also be made of glass, as a sheet, plate, block or as glass wool, orof silica. In the case of glass, glass is obtained with a hydrophobicouter face which does not retain water.

The invention may be the subject of very many other practicalapplications. A cellulosic fibrous structure according to the inventionmay accordingly for example serve to provide undergarments, towels orprotective cloth.

In addition, it may serve to provide dressings impermeable to water andto aqueous solutions and permeable to gases. Such a dressing isparticularly effective in as much as it prevents any bacterialcontamination by aqueous solutions and facilitates healing, taking intocontact its gas penneability properties.

The invention makes it also possible to obtain, in an alternative mannerto previously known waterproofing methods, clothing, which isimpermeable to water, and, the invention makes it possible to obtaintextile structures impermeable to water and permeable to air.

The invention also makes it possible to obtain a hydrophobic paperpermeable to gases, which may or may not be biodegradable and which mayor may not be colored. Such a paper may be the subject of very manyapplications, and in particular for packagings impermeable to water andaqueous solutions and permeable to air, or for a package or bagimpermeable to water and to aqueous solutions, which is biodegradable.

The invention is applicable to printing paper. Printing paper commonlyused in printers, photocopiers, and in printing works and for writingmust have a partially hydrophobic character. The purpose of this is topermit the diffusion of water-based inks into the texture of the paperbut in a controlled manner so that the ink does not spread out as may beobserved for example on blotting paper. This partially hydrophobiccharacter is obtained in the prior art by adding hydrophobic additivessuch as alkyl ketene dimers, long chain derivatives of succinicanhydride or compounds of the rosin family. All these compounds areadded to the cellulose in aqueous suspension, which presentsconsiderable technical problems taking into account the stronglyhydrophobic and water insoluble character of these additives. It is thusdesirable to have available a method which will enable this partiallyhydrophobic character to be provided with a method not requiring the useof an aqueous suspension. This partially hydrophobic character may beprovided by a method according to the invention using small quantitiesof grafting reagents.

In addition, since a solid material according to the invention ishydrophobic, it is in general also lipophilic. Accordingly, the solidmaterial according to the invention may be applied in all cases wherefat absorption properties are desired.

The invention provides a solid composition, which may be in divided formfor absorbing hydrocarbons which has a density less than that of water,for example, a hydrophobic wood chip or sawdust composition absorbinghydrocarbons and oils and capable of floating on the surface of water.Such a composition may serve in particular for the treatment of waterpollution by hydrocarbons.

The invention also concerns a treatment method and a solid materialwherein all or part of the characteristics mentioned above andhereinafter are combined.

As used herein, the term “about” or “approximately” means within anacceptable error range for the particular value as determined by one ofordinary skill in the art, which will depend in part on how the value ismeasured or determined, i.e., the limitations of the measurement system.For example, “about” can mean within 1 or more than 1 standarddeviations, per the practice in the art. Alternatively, “about” can meana range of up to 20%, preferably up to 10%, more preferably up to 5%,and more preferably still up to 1% of a given value. Alternatively, theterm can mean within an order of magnitude, preferably within 5-fold,and more preferably within 2-fold, of a value.

EXAMPLES

The following Examples illustrate the invention, but are not limiting.

Example 1 Production of Handsheet Web#1 Materials

1. CARESSA® 1100 available from Buckeye Technologies Inc. of Memphis,Tenn. CARESSA® 1100 is a type of chemically treated cellulose fiber,which was originally developed for use in absorbent structures and isdescribed in U.S. Pat. No. 6,562,743 and a published counterpart, WO00/38607, both of which are hereby incorporated by reference in theirentirety. CARESSA® 1100 is also referred to as SW or SW-16. In thepreparation of CARESSA® 1100, which is based on FOLEY FLUFFS®, aluminumsulfate is added to a slurry of cellulose fibers and the pH is adjustedso that aluminum hydroxide is precipitated on the fibers. Thepreparation is completed by the addition of citric acid.2. CARESSA® 3100 available from Buckeye Technologies Inc. of Memphis,Tenn. CARESSA® 3100 is a type of chemically treated cellulose fiber,which was originally developed for use in absorbent structures and isdescribed in U.S. Pat. No. 6,562,743 and a published counterpart, WO00/38607, both of which are hereby incorporated by reference in theirentirety. CARESSA® 3100 is also referred to as SW-25. In the preparationof CARESSA® 3100, which is based on FOLEY FLUFFS®, aluminum sulfate isadded to a slurry of cellulose fibers and the pH is adjusted so thataluminum hydroxide is precipitated on the fibers. The preparation iscompleted by the addition of an aqueous mixture of sodium hypophosphiteand aluminum sulfate.3. HPF™ is a mercerized cellulose fiber available from BuckeyeTechnologies Inc. of Memphis, Tenn.4. FOLEY FLUFFS® is cellulose fluff pulp available from BuckeyeTechnologies Inc. of Memphis, Tenn.5. FFLE™ and FFLE+™ based on FOLEY FLUFFS® and has added theretoaluminum sulfate as a debonding agent to lower the disintegration energyof the comminution sheet. This is described in U.S. Pat. No. 6,159,335,which is hereby incorporated by reference herein in its entirety.6. RB265-30W (merge #4591, 30 gsm) is a wettable synthetic polypropylenenonwoven carrier from American Nonwovens Corporation, Columbus, Mich.7. Polyester fiber from Kosa, Salisbury, N.C. merge #35379A, 6.7 dtex, 4mm.8. Bicomponent AL Delta binder fiber, 6.7 dtex, 6 mm, with apolypropylene core and polyethylene sheath from FiberVisions a/s, Varde,Denmark.9. Trevira bicomponent binder fiber, merge #1663, 2.0 dtex, 3 mm, is afiber with a polyester core and a polyethylene sheath from TreviraNeckelmann a/s, Silkeborg, Denmark.10. Tylac-NW-4036-51B is an emulsion of a styrene-butadiene terpolymerfrom Dow Reichhold, Durham, N.C.11. Artilene blue pigment 6825-9 paste from Clariant Corp., Charlotte,N.C.12. 18 gsm cellulose tissue (Cellutissue 3024) is supplied by CelluTissue Holdings, Inc., East Hartford, Conn.13. ND416 cellulose fluff (Weyerhaeuser Co., Tacoma, Wash.).14. Polyester fiber (Kosa, merge #35379A).15. AF 192 is an emulsion of an ethyl vinyl acetate copolymer from AirProducts and Chemicals, Inc., Allentown, Pa.16. EP 1188 is an emulsion of a vinyl acetate copolymer from AirProducts and Chemicals, Inc., Allentown, Pa.17. Coverstock material 22 gsm is a through-air-bonded carded websupplied from Sandler AG, Schwarzenbach/Saale, Germany.

Methods

Handsheets of Web #1 were produced on a laboratory airlaid formingdevice by depositing the following layers on a wettable syntheticnonwoven carrier RB265-30W, merge #4591, 30 gsm, from American NonwovensCorporation, Columbus, Mich.:

-   Layer 1: Blend of 14.7 gsm polyester fiber (Kosa, merge #35379A, 6.7    dtex, 4 mm) and 30.3 gsm bicomponent AL Delta binder fiber (6.7    dtex, 6 mm) from FiberVisions a/s, Varde, Denmark.-   Layer 2: Blend of 34.7 gsm mercerized cellulose fiber (Buckeye, HPF)    and 3.5 gsm Trevira bicomponent binder fiber (merge #1663, 2.0 dtex,    3 mm), from Trevira Neckelmann a/s, Silkeborg, Denmark.-   Layer 3: Blend of 38.1 gsm cellulose fluff (Buckeye, Foley Fluffs)    and 3.5 gsm Trevira bicomponent binder fiber (merge #1663).    The sheets were pressed slightly and cured in the lab convection    oven at 150° C. for 15 minutes. The density of the sheets was 0.035    g/cm³.

Example 2 Coating Handsheet Surfaces

The surface of some of the handsheets produced following the proceduredescribed in Example 1 was coated on the carrier side with a foam havingthe following formulation: 10% solids content of Tylac-NW-4036-51B fromReichhold plus 0.52% of latex solids content of Artilene blue pigment6825-9 paste from Clariant Corp., Charlotte, N.C. The blue foam wasapplied in stripes similar to those shown in FIG. 1A. The width of eachstripe was 5 mm and a space between each pair of adjacent stripes wasalso 5 mm. The handsheets were cured in the lab convection oven at 140°C. for 5 minutes. The samples were designated as Web #2 and had adensity of 0.040 g/cm³.

Example 3 Demonstration of Wettable Zones

In FIG. 1A, one example of this invention is shown which is web #2. Thesurface of web #2 comprises one or more regions of more wettable zonesthrough which body fluid or its stimulant can flow easily for efficientfluid intake, and less wettable zones through which the flow of theliquid is reduced or the liquid does not penetrate. These zones aredesigned for reduced flow back to the surface and lower rewet.

The more wettable zones are understood here as zones, which can bewetted relatively easily with a liquid to be absorbed. The less wettablezones are zones, which are not wetted as easily with the liquid, in thisexample the blue stripes of hydrophobic latex. In other words, thecontact angle between the liquid and the surface of a more wettable zonewill be lower than the contact angle between the liquid and the lesswettable zone. As a result the liquid will tend to run on the surface ofthe structure from a less wettable zone toward a more wettable zone assoon as it gets in contact with such a more wettable zone. The effect ofthis controlled wetting is that the surface of the less wettable zoneswill remain drier than the surface of the more wettable zones. This willcreate a visual effect of improved stain hiding and dryness of thesurface of the structure. Optionally, the different zones can be mademore visible to the consumer, for example, by using different colors formore wettable and for less wettable zones, creation of various shapes ortexture of these zones or by other techniques.

The effect described above is illustrated in FIG. 1A, where the morewettable zones are white stripes whereas the less wettable zones areblue stripes. The colors of the more wettable and less wettable zones,their shape and pattern may vary depending on consumer preference and onthe creativity of the manufacturer. Another example is shown in FIG. 1C,in which the sample was made as web #2 in Example 2, but without theblue pigment.

Example 4 Formation of Handsheet Web#3

Handsheets of Web #3 were produced on a laboratory airlaid formingdevice with a profiled forming screen having a pattern as reflected inthe material produced with it shown in FIG. 2. The protrusions P hadeach a diameter of 3 mm in diameter and a height of 2 mm. The distancebetween the axes of adjacent protrusions was 5 mm.

Profiled forming screens of this type and associated techniques for theproduction of materials using them are disclosed in U.S. Ser. No.60/493,875 filed Aug. 8, 2003, which is hereby incorporated by referenceherein in its entirety.

The following layers of fibers were deposited on the forming screen:

-   Layer 1: Blend of 18.1 gsm polyester fiber (Kosa, merge #35379A) and    37.3 gsm bicomponent AL Delta binder fiber (6.7 dtex, 6 mm).-   Layer 2: Blend of 42.7 gsm mercerized cellulose fiber (Buckeye, HPF)    and 4.3 gsm Trevira bicomponent binder fiber (merge #1663).-   Layer 3: Blend of 38.1 gsm cellulose fluff (Buckeye, Foley Fluffs)    and 3.5 gsm Trevira bicomponent binder fiber (merge #1663).

The sheets were pressed slightly and cured in the lab convection oven at150° C. for 15 minutes. The density of the sheets was 0.038 g/cm³.

Example 5 Coating of Synthetic-Sided Handsheets

The surface of some of the handsheets produced following the proceduredescribed in Example 4 was coated on the synthetic fiber side with anaqueous foam containing the following ingredients: 10% solids content ofTylac-NW-4036-51B from Reichhold plus 0.52% of latex solids content ofArtilene blue pigment 6825-9 paste from Clariant Corp., Charlotte, N.C.

The foam was applied onto the top surface of the web leaving theindentations uncoated as illustrated in FIG. 3A. The handsheets werecured in the lab convection oven at 140° C. for 5 minutes. The obtainedsamples were designated as Web #4 and had a density of 0.039 g/cm³.

Example 6 Production of Handsheets

Handsheets of Web #5 were made in a way similar to that used for makingWeb #3 except for the type of the forming screen used. The formingscreen used to prepare Web #5 was a regular, flat screen. As a resultthe surface of Web #5 was flat. The density of the samples of Web #5 was0.036 g/cm³.

FIG. 3A illustrates another example of more wettable and less wettablezones, where the less wettable zones were obtained by treating parts ofthe surface with a hydrophobic polymer containing a blue pigment. Inthis example the surface is not flat but textured and the zones coatedwith the hydrophobic polymer are higher than the uncoated, more wettablezones. The red liquid stain is hidden better behind the less wettablezones. The control material in FIG. 3B does not have textured surfaceand was produced in such a way that its surface had uniform wettability.

FIG. 4A illustrates an example of the structure of the invention, whichis composed of an upper acquisition layer (AL) and a bottom storagelayer (SL). Handsheets of a storage layer (SL) were prepared on alaboratory forming device by using 18 gsm cellulose tissue (Cellutissue3024) and depositing on it a blend of 414 gsm ND416 cellulose fluff(Weyerhaeuser Co., Tacoma, Wash.), and 46 gsm Trevira bicomponent fiber(merge #1663). The web was pressed and cured in the lab oven at 150° C.for 15 minutes. The final density of the sheets was 0.15 g/cm³.

The upper acquisition layer (AL) was made on a lab equipment bydepositing 102 gsm CARESSA 3100® fiber blended with 18 gsm Trevirabicomponent fiber (merge #1663) on the forming screen with protrusionsdescribed in Example 4. The web was pressed and cured in the lab oven at150° C. for 15 minutes. The final density of the acquisition layer (AL)was 0.055 g/cm³. The chromatographic analysis of the finish on thebicomponent fibers, as received from the supplier of those fibers,revealed that the finish contained methyl oleate. It is hypothesizedthat during the curing process of the acquisition layer (AL) methyloleate reacted with Al ions in the CARESSA 3100® rendering the surfaceof the acquisition layer (AL) hydrophobic. In the structure shown inFIG. 4A, the upper acquisition layer (AL) is in close contact with thehydrophilic storage layer (SL) at the indentations of the acquisitionlayer (AL) structure. Thus, the liquid can penetrate easily throughthese indentations. On the other hand, the protrusions of theacquisition layer (AL) are farther from the hydrophilic storage layer(SL) and therefore they produce the desired stain masking effect due totheir hydrophobic surface. The photograph in FIG. 4A shows the effect ofstain hiding produced by the acquisition layer (AL). FIG. 4B is aphotograph of a structure comprising an upper layer having flat surfaceand being wettable on its whole area.

Example 7 Testing Rewet Characteristics

The following procedure was applied to test the rewet characteristics ofvarious samples: An apparatus called Fluid Intake Tester (FIT) was usedto test the experimental samples. The FIT consists of a top and a bottomboard, which are made of a transparent plastic material such as lexar orplexiglass. The opening diameter for the dose intake tube is 25 mm. Theupper plate weighs 872 g. The top FIT board is illustrated in FIGS. 5Aand 5B. FIG. 5A is an image of the top view, and FIG. 5B is an image ofthe side view of the board. The end of the inlet tube (9) is flush withthe bottom of the top FIT board. The lower FIT board should be a flatrectangular piece of clear plastic with dimensions similar to thedimensions of the upper board contour. The length of the upper board was29.7 cm, its width was 19 cm and its thickness was 1.2 cm. The inlettube (9) was fixed in the center of the top board. The total height ofthe tube (9) was 6 cm.

Each tested sample had dimensions of 70 mm in width and 200 mm inlength. It was placed on a storage layer made as described in Example 3.The width of the storage layer was 35 mm and its length was 100 mm. Thetested sample (10) and the storage layer (11) were aligned as shown inFIG. 6. The test sample and the storage layer were then covered with acoverstock material, a through-air bonded carded web having basis weightof 22 gsm from Sandler AG, and the whole system was placed between thebottom and the upper FIT boards. Each tested sample system was theninsulted through the inlet tube with 10 cm³ of synthetic menses stocksolution. This was an aqueous solution containing 0.38% red dye BiebrichScarlet, obtained from Sigma, Catalogue No. B-6008, 0.9% sodium chlorideand 11.8% polyvinylpyrrolidone (PVP) having molecular weight of 55,000and viscosity in a range of 9.0 cP to 10.0 cP. After waiting for 20minutes approximately 45 g of pre-weighed Buckeye grade S-22, a 22 gsmcellulose blotter paper, available from Buckeye Technologies, cut to10.2 cm by 214.1 cm was placed on top of the sample for 2 minutes underload of 2.8 kPa. The load was composed of a spongy solid foam layer toensure uniform pressure over the whole area of the sample and of aweight. After 2 minutes, the load was removed and the blotter paper wasweighed. The difference in weight of the blotter paper before and afterthe test is the rewet value.

The results of the tests are presented in Table 2. The data indicatethat the dryness of Web #2 was better, with a lower rewet, than thedryness of the control Web #1, which had a higher rewet. The resultsshow that Web #4 had the best dryness in the rewet test and the controlWeb #5 had higher rewet than both Web #3 and Web #4.

TABLE 2 Sample Web Number Rewet, g 1 1.03 2 0.70 3 050 4 040 5 063

Example 8 Production of Handsheet Web#6

Handsheets of Web #6 were produced on a laboratory airlaid formingdevice by depositing the following layers:

-   Layer 1: Blend of 27 gsm SW16 cellulosic fiber (Buckeye) and 8.5 gsm    Trevira bicomponent binder fiber (merge #1663).-   Layer 2: Blend of 35 gsm FOLEY FLUFFS® cellulosic fiber (Buckeye)    and 2 gsm Trevira bicomponent binder fiber (merge #1663).-   Layer 3: Blend of 8 gsm SW16 cellulosic fiber (Buckeye) and 2 gsm    Trevira bicomponent binder fiber (merge #1663).

The web was pressed to a thickness of 0.8 mm. It was then sprayed with1.5 gsm (by solids weight) of AF 192 binder (Air Products) on thesurface of Layer 3 and sprayed with 1.5 gsm (by solids weight) of EP1188binder on the surface of Layer 1. The sheet was cured in the labconvection oven at 150° C. for 15 minutes. The sheet of web #6 had awettable surface on the side of Layer 3 and a hydrophobic surface on theside of Layer 1.

One milliliter of the synthetic menses stock solution described inExample 7 was poured on the wettable surface of web #6. The structureacquired the liquid, which then became contained in the web and did notpenetrate through the opposite, hydrophobic side. The liquid stain wasalso less visible on the hydrophobic side than on the hydrophilic,wettable side.

The stain masking effect was due to the hydrophobicity of Layer 1 andthe hydrophobic nature of the EP1188 binder applied on the outer surfaceof this layer. It is hypothesized that the presence of Al ions in SW16fiber and methyl oleate in the formulation of the finish of thebicomponent binder fiber were responsible for the hydrophobicity ofLayer 1. As explained earlier, this hydrophobicity was probably due tothe reaction between the Al ions and methyl oleate of the finish in thebicomponent fibers during the curing stage. Layer 3 containedsignificantly lower content of bicomponent fiber and the amount offinish containing methyl oleate was not sufficient to produce thehydrophobic effect with the Al ions on the SW16 fibers.

Example 9 Production of Handsheet Web#7

Handsheets of Web #7 were produced on a pilot Dan Web airlaid formingequipment by depositing the following layers:

-   Layer 1: Blend of 10 gsm polyester fiber, Kosa, merge #35379A, 6.7    dtex, 4 mm, and 20 gsm bicomponent AL Delta binder fiber, 6.7 dtex,    6 mm, from FiberVisions a/s, Varde, Denmark.-   Layer 2: Blend of 40 gsm cellulose fiber, FOLEY FLUFFS® and 10 gsm    Trevira bicomponent binder fiber, merge #1663, 2.0 dtex, 3 mm, from    Trevira Neckelmann a/s, Silkeborg, Denmark.-   Layer 3: Blend of 41.5 gsm cellulose fluff, FOLEY FLUFFS® and 4.0    gsm Trevira bicomponent binder fiber, merge #1663.

Liquid binder AF-192 (Air Products) was sprayed at 10% solids on thesurface of Layer 3 in an amount of 1.5 gsm based on the dry solidsweight. The sheets were pressed slightly and cured in the lab convectionoven at 150° C. for 15 minutes. The density of the sheets was 0.035g/cm³.

A foam was prepared with Tylac-NW-4036-51B latex (Reichhold) at 15%solids by weighing 84.6 g latex (53% solids) and diluting it with 300 gand beating the mixture in a cake mixer on maximum speed for 3 minutes.A small handsheet was cut out of Web #7. The surface of Layer 1 wassubsequently covered with a template with openings masking a part of thearea to produce a “flower” pattern. Then the foam of Tylac-NW-4036-51Blatex was spread evenly over the entire surface. The excess foam wasremoved by lightly scraping the surface with a spatula and the samplewas placed in an oven at 145° C. for 15 minutes. After curing, aphotograph was taken of the top surface of the sheet and then a coloredliquid was applied on its surface. When the liquid was absorbed anotherphotograph was taken to show the masking effect produced by thetreatment of the sheet. The photographs are displayed in FIG. 7.

Example 10 Treating Handsheets

A 10% aqueous solution of sodium oleate was sprayed onto one half of thefront of a 5″×8″ piece of SW-16 pulp sheet, lot #625649, available fromBuckeye Technologies Inc. The sheet was placed in a drying oven at 70°C. for 15 minutes. After the pulp sheet cooled to ambient temperature, adrop of water was placed on the untreated half of the pulp sheet. Itimmediately soaked into the pulp sheet. A drop of water placed on thetreated half of the pulp sheet remained on the surface with a very highcontact angle.

Example 11

Using the laboratory airlaid forming device homogeneous sheets wereprepared, each having a basis weight of 150 gsm. The composition andthickness of each sheet is shown in Table 3. The sheets containingbicomponent binder fibers were cured in a laboratory convection oven at150° C. The times of curing are given in Table 3. The sheets were thentested for permeability of defibrinated sheep blood. Each sheet wasplaced on a beaker so that the liquid could penetrate through it anddrop into the beaker. The defibrinated sheep blood in an amount of 6 mLwas poured from a narrow cylinder onto the top of each sheet and thetime was measured from the moment the whole amount of blood wasdeposited on the sheet until the moment the liquid started to drop intothe beaker from the bottom side of the sheet. This time was calledstrike-through time and is recorded in Table 3. After the whole amountof blood passed through the sheet the diameter of the stain on the topside of the sheet was measured and the results are contained in Table 3.Based on the data given in Table 3 the conclusion can be drawn that thesheets made with CARESSA 3100® fibers and bonded with bicomponent fiberhad a higher permeability than the unbonded sheets and the bonded sheetsmade with FOLLY FLUFFS® and bicomponent fibers. It is thought that thiseffect was due to the fact that the bicomponent fiber contained afatty-acid based finish which reacted with the Al ions on the CARESSA3100® fibers. As a result of this reaction the stability of the bondedweb comprising CARESSA 3100® fibers was enhanced due to additionalinter-fiber bonds thus preventing it from collapsing. Another aspect ofthe fatty-acid metal ion interaction is that the reaction between thefinish on the bicomponent fibers and the Al ions on the CARESSA 3100®fibers lowered the surface energy of the fibers. This in turn inhibitedthe wicking of the liquid in the planar direction within the web andresulted in a small stain size.

TABLE 3 Curing Top stain Thickness, time, Strike-through diameter, Sheetcomposition mm minutes time, seconds mm FF*) 1.40 0 54.7 80 SW-25**)1.42 0 61.0 90 FF 75%/Bico***) 25% 1.87 0 85.2 60 FF 75%/Bico 25% 1.885.0 86.2 90 SW-25 75%/Bico 25% 1.83 1.5 20.3 30 SW-25 75%/Bico 25% 1.834.0 26.4 30 *)FF—FOLLY FLUFFS ® **)SW-25 - CARESSA 3100 ®***)Bico—Trevira bicomponent fiber

Example 12 Testing Tensile Strength

Using the laboratory airlaid forming device homogeneous sheets wereprepared, each having a basis weight of 100 gsm and a density of 0.045g/cm³. The composition of each sheet is shown in Table 4. The sheetscontaining bicomponent binder fibers were cured in a laboratoryconvection oven at 150° C. for the times given in Table 4. The sheets,each 2.5 cm wide and 10 cm long, were then tested for tensile strengthand the results are recorded in Table 4. These results suggest that theamount of curing time necessary to obtain the maximum tensile strengthis significantly less in the case of the webs comprising the SW-16fibers than in the case of the webs which do not contain these fibers.One can postulate that the curing process provides conditions for rapidcreation of additional bonds between the fibers in the web. It is quitelikely that this effect is associated with the interaction between theAl ions on the SW-16 fibers and the fatty-acid containing finish on thebicomponent fibers. As a result, not only the time of curing can bereduced but the tensile strength is higher than that of the webs whichdo not comprise fibers with Al ions.

TABLE 4 Tensile strength, N, after curing for Sheet composition 3 min 7min 10 min SW-16 95%/Bico*) 5% 0.8 1.3 1.3 SW-16 90%/Bico 10% 2.7 3.83.3 SW-16 85%/Bico 15% 7.2 6.5 5.5 FF**) 95%/Bico 5% 0.3 0.8 1.0 FF90%/Bico 10% 0.4 2.8 3.1 FF 85%/Bico 15% 0.8 5.0 5.3 *)Bico—bicomponentfiber **)FF—FOLLY FLUFFS ®

Example 13 Testing Tensile Properties

50 grams of sodium oleate flake from Norman, Fox & Co. was mixed withdistilled water to form a 10% sodium oleate solution with stirring andheating to completely dissolve the flake. The 10% solution was sprayedat a loading 1.0 part of sodium oleate per 100 parts of fiber onto onesurface of a sheet of CARESSA® 1100 fiber, obtained from BuckeyeTechnologies Inc., which had an aluminum content of 7,685 ppm and acitric acid content of 4.5%. Sheets were also prepared with loadings of0.5 part per 100 parts of fiber and 0.25 part per 100 parts of fiber.

The 10% sodium oleate solution was sprayed at a loading 1.0 part ofsodium oleate per 100 parts of fiber onto one surface of a sheet ofFoley Fluffs®, obtained from Buckeye Technologies Inc. Sheets were alsoprepared with loadings of 0.5 part per 100 parts of fiber and 0.25 partper 100 parts of fiber.

The 10% sodium oleate solution was sprayed at a loading 1.0 part ofsodium oleate per 100 parts of fiber onto one surface of a sheet ofFoley Fluffs® containing precipitated aluminum, obtained from BuckeyeTechnologies Inc., which had an aluminum content of 7,827 ppm. Sheetswere also prepared with loadings of 0.5 part per 100 parts of fiber and0.25 part per 100 parts of fiber.

The pulp sheets were allowed to air-dry overnight at a room temperatureof 22° C. Handsheets were made from each fiber according to TAPPI MethodT205 except that a 0.5% consistency slurry was used during thedisintegration step and the handsheets were not pressed.

The following properties were measured on the unpressed TAPPIhandsheets: permeability (cfm/ft.²), dry tensile (g/in), bulk (cc/g),initial wet tensile (g/in) and 5-minute wet tensile (g/in). Permeabilitywas determined using an air permeability tester. Specifically, fourhandsheets per experimental fiber were tested in the air permeabilitytester. For each handsheet a pressure drop of one half inches of waterwas established across the handsheet and air flow through the sheet wasmeasured by the pressure drop across an orifice indicated on a verticalmanometer. The average manometer reading was converted to airpermeability using conversion tables. This method is described in U.S.Pat. No. 6,171,441 which is hereby incorporated by reference herein inits entirety. Dry tensile values were determined using TAPPI MethodT494. Wet tensile values were determined using TAPPI Method T456,pre-1997 edition.

The results in Tables 5 and 6 showed that adding sodium oleate to thefibers did not significantly impact permeability, dry tensile or bulk.The wet tensile strength showed an increase when sodium oleate was addedto fibers containing aluminum. The following graph depicts theinteraction between sodium oleate and aluminum containing fibers.

TABLE 5 Wet Tensile Data (g/in) Sodium Oleate Add-on Fiber 0% 0.25%0.50% 1.00% Foley Fluffs ® 13 18 19 13 Caressa 1100 28 168 244 261 FoleyFluffs ® 54 32 233 270 with Aluminum

TABLE 6 Contact Angle Data Sodium Oleate Add-on Fiber 0% 0.25% 0.50%1.00% Foley Fluffs ® 27.0 24.0 21.2 41.1 Caressa 1100 Too fast 97.5113.4 118.8 Foley Fluffs ® Too fast 92.4 101.6 105.6 with Aluminum

Example 14

Cellulose fibers were treated as follows. A total of 9.36 parts hydratedaluminum sulfate (Al₂(SO₄)₃*14H₂O) from General Chemical Corporation,per 100 parts bleached southern softwood Kraft (13SSK) fibers fromBuckeye Technologies were added to a slurry consisting of 4.5 partsfiber/100 parts slurry. The slurry had a pH of 3.2. After 25 minutes ofmixing 3.0 parts sodium hydroxide/100 parts fiber were added along withsufficient water to provide 0.9 parts fiber/100 parts slurry at a pH of5.7. The temperature was adjusted to 60° C. The resultant slurry wascontinuously dewatered on a sheeting machine where the sheet was formedat 1.0 rush/drag ratio, couched, then pressed and densified using threestages of pressing to 48 parts fiber/100 parts total. The sheet wasdried using conventional drum dryers to 93.5 percent solids. Whilecontinuously reeling, a spray of heated 10% aqueous sodium oleate (fromNorman, Fox & Co.) solution was applied to one surface of the sheet at aloading of 1.0 part per 100 parts of fiber. The reeled sheet was thensized into individual rolls. The fiber was found to be hydrophobic andexhibited significant wet strength.

Example 15

A slurry of bleached southern softwood Kraft (BSSK) fibers from BuckeyeTechnologies consisting of 4.5 parts fiber/100 parts slurry was dilutedwith sufficient water to provide 0.9 parts fiber/100 parts slurry andadjusted to a pH of 5.5. The resultant slurry was continuously dewateredon a sheeting machine and a sheet was formed at a rush/drag ratio of1.0, couched, then pressed and densified through three stages ofpressing to 48 parts fiber/100 parts slurry. The sheet was dried usingconventional drum dryers to 93.5 percent solids. The sheet was thenreeled. During reeling, 6.1 parts of hydrated aluminum sulfate(Al₂(SO₄)₃*14H₂O, 50% aqueous solution) and 1.0 part of heated sodiumoleate (10% aqueous solution) are applied by spraying per 100 parts. Thefiber was reeled on a continuous roll. The reeled sheet was then sizedinto individual rolls. The sheet became hydrophobic after treatment.

Example 16

Cellulose fibers were treated as follows. A total of 9.36 parts hydratedaluminum sulfate (Al₂(SO₄)₃*14H₂O) from General Chemical Corporation and3 parts of (10% aqueous sodium oleate) solution per 100 parts bleachedsouthern softwood Kraft (BSSK) fibers from Buckeye Technologies wereadded to a slurry consisting 4.5 parts fiber/100 parts slurry. Theslurry had a pH of 3.2. After 25 minutes of mixing 3.0 parts sodiumhydroxide/100 parts fiber were added along with sufficient water toprovide 0.9 parts fiber/100 parts slurry at a pH of 5.7. The temperaturewas adjusted to 60° C. The resultant slurry was continuously dewateredon a sheeting machine where the sheet was formed at 1.0 rush/drag ratio,couched, then pressed and densified using three stages of pressing to 48parts fiber/100 parts total. The sheet was dried using conventional drumdryers to 93.5 percent solids. The reeled sheet was then sized intoindividual rolls. As a result of this treatment, the paper becamehydrophobic.

Example 17

12.1 g of ferric nitrate (Fe(NO₃)₃) Fisher Chemical Co.) per 152 gbleached southern softwood Kraft (BSSK) fibers from Buckeye Technologieswere added to a slurry of 4.5 parts fiber/100 parts slurry. The slurryhad a pH of 2.76. After mixing and dilution to 0.9 parts fiber/100 partsslurry, 27.1 ml of 10% sodium hydroxide were added to provide a pH of5.7. The resultant slurry was dewatered on a dynamic handsheet former(Formette Dynamique Brevet, Centre Technique de L'Industrie, Ateliers deConstruction Allimand, Appareil No. 48) and was pressed to 48 partsfiber/100 parts total. The sheet was dried to 93.5 percent solids. Afterdrying, 1 part of 10% aqueous sodium oleate solution per 100 parts offiber was applied to the sheet.

Example 18

9.36 parts hydrated aluminum sulfate (Al₂(SO₄)₃*14H₂O) per 100 partsbleached southern softwood Kraft (BSSK) fibers from Buckeye Technologieswere added to a slurry consisting of 4.5 parts fiber/100 parts slurry.After addition of the aluminum sulfate, the slurry had a pH of 3.2.After 25 minutes of mixing, 3.0 parts sodium hydroxide/100 parts fiberwere added along with sufficient water to provide 0.9 parts fiber/100parts slurry at a pH of 5.7 and temperature of 60° C. The resultantslurry was continuously dewatered on a sheeting machine and a sheetformed at a 1.0 rush/drag ratio, couched, then pressed and densifiedusing three stages of pressing to 48 parts fiber/100 parts total. Aspray of heated 10% aqueous sodium oleate solution was applied to onesurface of the sheet at a loading of 1.0 part per 100 parts of fiber.The sheet was dried to 93.5 percent solids. As a result of thistreatment, the paper became hydrophobic.

Example 19

High porosity commercial fiber (HPZ) was obtained from BuckeyeTechnologies Inc. in sheet form. The fibers had a WRV of 78.3, a curl of51% and a 97.9% alpha cellulose content. A total of 9.36 parts ofaluminum sulfate (Al₂(SO₄)₃*14H₂O) per 100 parts fiber were added to aslurry of 4.5 parts fiber/100 parts slurry. The slurry had a pH of 3.2.After 25 minutes of mixing, 3.0 parts sodium hydroxide/100 parts fiberwere added along with sufficient water to provide 0.9 parts fiber/100parts slurry at a pH of 5.7. The resultant slurry was dewatered on adynamic handsheet former (Formette Dynamique Brevet, Centre Technique deL'Industrie, Ateliers de Construction Allimand, Appareil No. 48) and waspressed to 48 parts fiber/100 parts total. The sheet was dried to 93.5percent solids. After drying, 1.0 part of heated sodium oleate (Norman,Fox & Co.) per 100 parts fiber were applied to the sheeted material byspraying.

Example 20

High purity commercial cotton fiber (GR512) was obtained from BuckeyeTechnologies Inc. in sheet form. A total of 7.7 parts of aluminumsulfate (Al₂(SO₄)₃*14H₂O) per 100 parts fiber were added to a slurry of4.5 parts fiber/100 parts slurry. The slurry had a pH of 3.2. After 25minutes of mixing, 3.0 parts sodium hydroxide/100 parts fiber were addedalong with sufficient water to provide 0.9 parts fiber/100 parts slurryat a pH of 5.7. The resultant slurry was dewatered on a dynamichandsheet former (Formette Dynamique Brevet, Centre Technique deL'Industrie, Ateliers de Construction Allimand, Appareil No. 48) and waspressed to 48 parts fiber/100 parts total. The sheet was dried to 93.5percent solids. After drying, 1.0 part of sodium oleate (Norman, Fox &Co.) per 100 parts fiber were applied to the sheeted material byspraying. The sheet was found to be hydrophobic and exhibited wetstrength.

Example 21

A slurry of bleached southern softwood Kraft (BSSK) fibers BuckeyeTechnologies consisting of 4.5 parts fiber/100 parts slurry was dilutedwith sufficient water to provide 0.9 parts fiber/100 parts slurry andadjusted to a pH of 5.5. The resultant slurry was continuously dewateredon a sheeting machine where the sheet was formed at a rush/drag ratio of1.0, couched, then treated by spraying with 12.35 parts of hydratedaluminum sulfate and 3.17 parts of sodium hypophosphite per one hundredparts of fiber, then pressed and densified through three stages ofpressing to 48 parts fiber/100 parts slurry. The sheet was dried usingconventional drum dryers to 93.5 percent solids. After drying, 1 part of10% aqueous sodium oleate solution per 100 parts of fiber was applied tothe sheet. The fiber was reeled on a continuous roll. The resultant reelwas sized into individual rolls.

Example 22

A slurry of bleached southern softwood Kraft (BSSK) fibers BuckeyeTechnologies consisting of 4.5 parts fiber/100 parts slurry was dilutedwith sufficient water to provide 0.9 parts fiber/100 parts slurry andadjusted to a pH of 5.5. The resultant slurry was continuously dewateredon a sheeting machine where the sheet was formed at a rush/drag ratio of1.0, couched, then treated by spraying with 12.35 parts of hydratedaluminum sulfate, 1.0 part of sodium oleate and 3.17 parts of sodiumhypophosphite per one hundred parts of fiber, then pressed and densifiedthrough three stages of pressing to 48 parts fiber/100 parts slurry. Thesheet was dried using conventional drum dryers to 93.5 percent solids.The fiber was reeled on a continuous roll. The resultant reel was sizedinto individual rolls.

Example 23

A total of 9.36 parts of hydrated aluminum sulfate (Al₂(SO₄)₃*14H₂O) per100 parts of bleached southern softwood Kraft (BSSK) fibers from BuckeyeTechnologies were added to a slurry consisting of 4.5 parts fiber/100parts slurry. The slurry had a pH of 3.2. After 25 minutes of mixing,3.0 parts of sodium hydroxide per 100 parts of fiber were added withsufficient water to provide 0.9 parts fiber per 100 parts slurry at a pHof 5.7 and at a temperature of 60° C. The resultant slurry wascontinuously dewatered on a sheeting machine where the sheet was formedat a rush/drag ratio of 1.0, couched, then treated by spraying with12.35 parts of hydrated aluminum sulfate and 3.17 parts of sodiumhypophosphite per one hundred parts of fiber, then pressed and densifiedthrough three stages of pressing to 48 parts fiber/100 parts slurry. Thesheet was dried using conventional drum dryers to 93.5 percent solids.After drying, 1 part of 10% aqueous sodium oleate solution per 100 partsof fiber was applied to the sheet. The fiber was reeled on a continuousroll. The resultant reel was sized into individual rolls.

Example 24

A slurry of bleached southern softwood Kraft (BSSK) fibers BuckeyeTechnologies consisting of 4.5 parts fiber/100 parts slurry was dilutedwith sufficient water to provide 0.9 parts fiber/100 parts slurry andadjusted to a pH of 5.5. The resultant slurry was continuously dewateredon a sheeting machine where the sheet was formed at a rush/drag ratio of1.0, couched, then pressed and densified through three stages ofpressing to 48 parts fiber/100 parts slurry, then treated by sprayingwith 12.35 parts of hydrated aluminum sulfate, 1.0 part of sodium oleateand 3.17 parts of sodium hypophosphite per one hundred parts of fiber.The sheet was dried using conventional drum dryers to 93.5 percentsolids. The fiber was reeled on a continuous roll. The resultant reelwas sized into individual rolls.

TABLE 7 Contact Angle Data - Different Add-on Techniques - DynamicHandsheet Sodium Oleate Add-on Fiber 0% 0.75% 1.50% 3.00% Foley Fluffs ®Too Fast 72.9 94.2 102.6 Fatty Acid co- precipitated with Aluminum FoleyFluffs ® Too fast 100.0 107.8 116.6 with Aluminum Fatty Acid sprayed onprior to drying Foley Fluffs ® Too fast 91.0 98.2 110.2 with AluminumFatty Acid sprayed on after drying Fiber 0% 1.50% 3.00% Sodium OleateAdd-on (5,000 ppm of Aluminum) - Dynamic Handsheets Foley Fluffs ® — 176168 Co-precipitated Foley Fluffs ® with Aluminum 42 245 279 Fatty Acidadded before drying Foley Fluffs ® with Aluminum 42 189 220 Fatty Acidadded after drying Sodium Oleate Add-on (10,000 ppm of Aluminum) -Dynamic Handsheets Foley Fluffs ® —  30 112 Co-precipitated FoleyFluffs ® with Aluminum 37  98 197 Fatty Acid added before drying FoleyFluffs ® with Aluminum 37 111 205 Fatty Acid added after drying

Description of Organic Acids Bound to Fibers by Organic Cations

Long chain saturated or unsaturated organic acids may be bound tocellulose fibers by precipitation or insolubilization with polyvalentmetal cations as described above. Similarly, long chain saturated orunsaturated organic acids may be bound to cellulose fibers byprecipitation or insolubilization with polyvalent organic cations.Examples of such organic cations are cationic starches, cationicpolyacrylamides or polydiallyldimethyl ammonium chlorides. Cationicstarches useful in the practice of this invention include the Redibond®family of dry strength polymers from National Starch & Chemical Company.Cationic polyacrylamides useful in the practice of this inventioninclude Baystrength™ dry strength polymers from Bayer Chemical Company.Polydiallyldimethyl ammonium chlorides useful in the practice of thisinvention include polydiallyldimethyl ammonium chlorides from AldrichChemical Company.

In general, the polyvalent organic cation must be soluble in water andform an insoluble product when mixed with the anion of an organic acid.This insoluble product will be retained on a surface such as that of acellulose fiber, when the two chemicals are combined in an aqueousmixture of the fibers.

Example 25

Cellulose fibers in an aqueous slurry with a solids content of from 1 to3 percent solids content are adjusted to pH of about 7 to 8, to maximizethe anionic content of the fibers. A polyvalent organic cationic havingcationic content in excess of the anionic content of the fibers andapproximately 0.5 weight percent based on the dry weight of the fibersis dissolved in water at the same pH as the fiber slurry and mixed withthe fiber slurry. After 30 minutes the maximum retention of polyvalentorganic cation is achieved, converting the fibers to an overall cationicsurface. A solution of the long chain organic acid in anionic form, forexample, the sodium salt, at the same pH as the fiber slurry is mixedwith the fiber slurry. After 30 minutes, the maximum retention oforganic acid anion to the cationized fibers is achieved. The fibers aredrained, washed, made into TAPPI handsheets and the contact angle isthen determined.

Example 26

Cellulose fibers in an aqueous slurry with a solids content of from 1 to3 percent solids content were adjusted to pH of about 7 to 8. A cationicstarch from the Redibond® product line, approximately 0.5 weight percentbased on the dry weight of the fibers, was dissolved in water at thesame pH as the fiber slurry and mixed with the fiber slurry. After 30minutes an aqueous solution of sodium laurate, approximately 0.1 weightpercent based on the dry weight of the fibers, at the same pH as thefiber slurry was mixed with the fiber slurry. After 30 minutes, thefibers were drained, washed, made into TAPPI handsheets and the contactangle was measured.

Example 27

A mixture of cellulose fibers in an aqueous slurry (1-3% solids content)and 0.1% weight percent based on dry fiber weight of sodium laurate weremixed and the pH adjusted to 7-8. A cationic starch from the Redibond®product line, 0.5 weight percent based on dry fiber weight, wasdissolved in water at the same pH as the fiber slurry and the solutionadded to the fiber sodium laurate mixture. After 30 minutes of mixing,the fibers were drained, washed, made into TAPPI handsheets and thecontact angle measured.

Example 28

Cellulose fibers in an aqueous slurry (1-3% solids content) wereadjusted to pH 7-8, to maximize the anionic content of the fibers. Acationic starch from the Redibond® product line, 0.5 weight percentbased on dry fiber weight, was dissolved in water at the same pH as thefiber slurry and mixed with the fiber slurry. After 30 minutes ofmixing, the fibers were drained washed and made into TAPPI handsheets.An aqueous solution of sodium laurate, 0.1 weight percent based on thedry weight of the fibers, at the same pH as the fiber slurry was sprayedonto handsheets made from the fiber cationic starch mixture. After onehour at ambient temperature, the sheets were dried to constant weight at50° C. The treated handsheets were then slurried in water at pH 7-8, thefibers were formed into TAPPI handsheets and the contact angles weremeasured.

Example 29

Cellulose fibers in an aqueous slurry (1-3% solids content) wereadjusted to pH 7-8, to maximize the anionic content of the fibers. Acationic polydiallydimethyl ammonium chloride, 0.5 weight percent basedon dry fiber weight, was dissolved in water at the same pH as the fiberslurry and mixed with the fiber slurry. After 30 minutes of mixing, thefibers were drained washed and made into TAPPI handsheets. An aqueoussolution of sodium laurate, 0.1 weight percent based on the dry weightof the fibers, at the same pH as the fiber slurry was sprayed ontohandsheets made from the fiber cationic starch mixture. After one hourat ambient temperature, the sheets were dried to constant weight at 50°C. The treated handsheets were then slurried in water at pH 7-8, thefibers were formed into TAPPI handsheets and the contact angles weremeasured.

Example 30 Vapor Phase Application

Dry cellulose fibers containing aluminum hydroxide are exposed to thevapor of molten oleic acid (stearic acid) for one hour. The vapor phaseorganic acid is bound to the aluminum on the fibers, and the fibers areformed into a handsheet. The contact angel of the produced fibers isthen determined.

Example 31 Medium Consistency Application

An aqueous slurry of aluminum hydroxide containing cellulose fibers (10%solids content) is mixed with an aqueous solution of sodium oleate (1wt. % on dry fiber basis) in a medium consistency high shear mixer, for15 seconds. The mixture is heated for one hour at 50° C., with 5 secondsof mixing every 15 minutes. The fibers are removed from the mixer andwashed well with hot water. The fibers are formed into a handsheet, andthe contact angle is then determined.

Example 32 Medium Consistency Application

An aqueous slurry of cellulose fibers (10% solids content) is mixed with1 wt. % (dry fiber basis) of aluminum sulfate octadecahydrate and placedin a medium consistency high shear mixer. Then, an aqueous solution ofsodium oleate (1 wt. % on dry fiber basis) is mixed with the fiberslurry in medium consistency high shear mixer, for 15 seconds. Themixture is heated for one hour at 50° C., with 5 seconds of mixing every15 minutes. The fibers are removed from the mixer washed well with hotwater. The fibers are formed into a handsheet, and the contact angle isthen determined.

Example 33 Medium Consistency Application

An aqueous slurry of cellulose fibers (10% solids content) is mixed with1 wt. % (dry fiber basis) of calcium chloride and placed in a mediumconsistency high shear mixer. Then an aqueous solution of sodium oleate(1 wt. % on dry fiber basis) is mixed with the fiber slurry in mediumconsistency high shear mixer, for 15 seconds. The mixture is heated forone hour at 50° C., with 5 seconds of mixing every 15 minutes. Thefibers are removed from the mixer and washed well with hot water. Thefibers are formed into a handsheet, and the contact angle is thendetermined.

Example 34 Medium Consistency Application

An aqueous slurry of cellulose fibers (10% solids content) is mixed withan aqueous solution of sodium oleate (1 wt. % on dry fiber basis) in amedium consistency high shear mixer, for 15 seconds. Then, an aqueoussolution of aluminum sulfate octadecahydrate (or calcium chloride) 1 wt.% on dry fiber basis is mixed with the fiber slurry in a mediumconsistency high shear mixer for 15 seconds. The mixture is heated forone hour at 50° C., with 5 seconds of mixing every 15 minutes. Thefibers are removed from the mixer and washed well with hot water. Thefibers are formed into a handsheet, and the contact angle is determined.

Examples 35 through 41 below further illustrate the invention, and, asused therein, “% weight/volume” is used to describe the concentration ofa given compound in grams per 100 mL of solvent. So, instead of saying“0.2% (weight/volume) solution of stearic acid in chloroform” we can say“solution of stearic acid in chloroform having concentration of 0.2 gstearic acid per 100 ml chloroform.

Example 35

A rectangular, 10 cm by 10 cm sample of wet laid paper having basisweight of about 100 gsm was made with Buckeye FFLE+™ pulp. The sheet wasimpregnated with 1 ml of a 0.2% (weight/volume) solution of stearic acidin chloroform. After evaporating the chloroform under the hood, thesheet was placed above a sintered glass under which a slight vacuum wasmaintained and a stream of air at 80-100° C. was passed by means of alaboratory hair drier through the sheet for a few seconds. As a resultof this treatment the paper became hydrophobic.

Example 36

The treatment was performed according to the invention on hydrophiliccotton, sawdust, a piece of board, a cellulose acetate filter andCellophane with stearic acid solution in chloroform in a stream of hotair coming from a hair drier as indicated in previous examples. Allthese materials became hydrophobic after treatment.

Example 37

A 1% (weight/volume) solution of perfluorooctanoic acid was prepared inchloroform, a piece paper made with Buckeye FFLE+™ cellulose was soakedquickly in it. Then the solvent was evaporated and the paper wassubjected to a stream of hot air at 140° C. for few seconds. The samplethus prepared was then tested for its oleophobic character by depositinga drop of vegetable oil on the surface. It was found that the oilremained on the surface of the paper without wetting it.

Example 38

A dual-flow spray nozzle was used, fed with stearic acid heated aboveits boiling point chloride at a liquid flow rate of 0.6 ml/min. A pieceof rectangular, 10 cm by 10 cm paper made with Buckeye FFLE+™ cellulosewas placed under the nozzle at a distance of 10 cm for a period of onesecond so that a quantity of about 10 mg was deposited on the paper. Thepaper was then placed in an oven for 15 seconds. The paper becamehydrophobic.

Example 39

A rectangular, 10 cm by 10 cm sample of wet laid paper having basisweight of about 100 gsm was made with Buckeye FFLE+™ pulp. The sheet wasimpregnated with 1 ml of a 0.2% (weight/volume) solution of sodiumoleate in water. The sheet was placed above a sintered glass under whicha slight vacuum was maintained and a stream of air at 80-100° C. waspassed by means of a laboratory hair drier through the sheet until thesheet was dry. As a result of this treatment the paper becamehydrophobic.

Example 40

A sample of air laid paper having basis weight of about 100 gsm was madeon a lab sheet forming equipment using 90 gsm Buckeye FFLE+™. The sheetwas sprayed on one side with 5 gsm based on the dry weight of binder(AF192, Air Products), cured at 140° C. for 10 minutes and then sprayedon the other side with 5 gsm based on dry weight of the same binder andcured again in the same conditions. The produced sheet was hydrophilic.A rectangular, 10 cm by 10 cm sample of the sheet was then sprayed witha microdispersion of 1 ml of a 0.2% (weight/volume) solution of sodiumoleate in water. The sheet was placed above a sintered glass under whicha slight vacuum was maintained and a stream of air at 80-100° C. waspassed by means of a laboratory hair drier through the sheet until thesheet was dry. As a result of this treatment the paper becamehydrophobic.

Example 41

Southern softwood cellulose (FOLEY FLUFFS®, Buckeye) sheet wasimpregnated with stearic acid by treating it with a microdispersion of a0.5% (weight/volume) solution of stearic acid in chlorophorm. The sheetwas then dried under the hood and disintegrated into fluff on a labequipment.

A sample of air laid paper having basis weight of about 100 gsm was madeon a lab sheet forming equipment using 47.5 gsm of the cellulosecontaining stearic acid, 47.5 gsm FFLE+™ and 5 gsm Trevira #1663bicomponent binder fiber. The airlaid sheet was cured at 140° C. for 10minutes by applying a stream of hot air. As a result of this treatmentthe whole sheet became hydrophobic.

Example 42 Measurement of Water Retention Value

One gram cellulose of known water content was disintegrated, put into a200 ml Erlenmayer flask and suspended in 100 ml distilled water. Thesuspension was agitated for 1 h at 20° C., then transferred to a G3sintered-glass disk to remove the excess water under reduced pressure.The sintered-glass disk was then transferred to a centrifuge tube andcentrifuged at 2000 G for 15 minutes. Subsequently the weight of themoist sample was determined. The water retention value was calculatedaccording to the formula:

${{WRV}(\%)} = \frac{\begin{pmatrix}{{{Mass}{\mspace{11mu}\;}{of}{\mspace{11mu}\;}{moist}{\mspace{11mu}\;}{sample}} -} \\{{Mass}{\mspace{11mu}\;}{of}{\mspace{11mu}\;}{dry}{\;\mspace{11mu}}{sample}}\end{pmatrix} \times 100}{{Mass}{\mspace{11mu}\;}{of}{\mspace{11mu}\;}{dry}{\mspace{11mu}\;}{sample}}$Three WRV measurements were taken for each fiber sample to get anaverage value.

Example 43 Measurement of Contact Angle

The hydrophobicity of cellulose is determined by measuring the contactangle between the water droplet meniscus and the surface of thecellulose sheet. The surface becomes hydrophobic, when the contact angleα exceeds 90° as illustrated in FIG. 11.

Contact angle measurements were done with Pocket Goniometer PG-1,according to ASTM D724 (Standard Test Method for Surface Wettability ofPaper). A drop (0.5 μl) of the test liquid (demineralized water) wasplaced on the surface of the tested handsheet. The resultant contactangle was measured from the optical micrograph of the drop. Seventymeasurements were done for each sample. The average contact angle andstandard deviation were calculated in each case.

Example 44 Preparation of Sodium Salts of Fatty Acids

Sodium hydroxide solution was prepared by addition of 6 moles NaOH (240g) to the mixture of 800 mL methanol and 200 mL water.

One gram of a fatty acid chosen from the list of fatty acids in Table 8was dissolved in 50 mL methanol. If the fatty acid was insoluble atambient temperature, the temperature of the mixture had to be raiseduntil a solution could be obtained.

TABLE 8 General Name Formula Structural Formula Lauric acid C₁₂H₂₄O₂

Myristic acid C₁₄H₂₈O₂

Palmitic acid C₁₆H₃₂O₂

Palmitoleic acid C₁₆H₃₀O₂

Stearic acid C₁₈H₃₆O₂

Oleic acid C₁₈H₃₄O₂

Linoleic acid C₁₈H₃₀O₂

Ricinoleic acid C₁₈H₃₃O₃

The prepared solution of the fatty acid was then added to the molarequivalent of sodium hydroxide dissolved previously in themethanol/water mixture. As a result the obtained product was sodium saltof the fatty acid, which will be called here also as “sodium soap”.Subsequent to that water was added to obtain a total of 1000 mL of thesodium soap solution.

As an example the following procedure was used to obtain a solution ofsodium stearate:

Take 1 g stearic acid (0.0035 mol), dissolve in 50 ml methanol at 60° C.Add 0.0035 mol NaOH/methanol solution (21.1 ml of prepared solution),and sufficient volume of water to obtain 1000 ml.

In addition to the sodium salts prepared in the above manner, acommercial sodium soap was used composed mainly of sodium oleate. Thischemical was supplied by Valley Products (Memphis, Tenn.). Itscommercial name is “Val Pro GM”. The name which is used in the followingexamples is also “Valpro”.

Example 45 Deposition of Aluminum Hydroxide on Cellulosic Fibers

Never-dried pulp (152 g by bone-dry weight) was added to 6 liters softwater and agitated to obtain a slurry at cellulose consistency of about2.5%. Then an aqueous solution of sulfuric acid having a concentrationof 10% by weight was slowly added to the pulp slurry until the pH was inthe range of 3.6 to 4.0. 5. After that appropriate amount of hydratedaluminum sulfate Al₂(SO₄)₃.18H₂O was introduced to the 6-liter slurry,depending on the targeted content of Al in cellulose. The amounts ofAl₂(SO₄)₃.18H₂O and the target contents of Al in the prepared cellulosepulp batches are given in Table 9.

The mixture was agitated for about 15 minutes. In the meantime 13 litersof demineralized water placed in a separate bucket and the pH adjustedto 3.5-3.7, using an aqueous solution of sulfuric acid at aconcentration of 10% by weight. The 6 liter slurry of fiber withAl₂(SO₄)₃.18H₂O was then transferred to the bucket with 13 liters ofwater adjusted to pH 35-3.7. The resultant slurry was adjusted to pH 3.5using again the 10% sulfuric acid solution. Then add, with agitation forabout 15 minutes, an aqueous solution of sodium hydroxide at aconcentration of 10% by weight to bring the pH up to 5.7+/−0.2.

TABLE 9 Amount of Al₂(SO₄)₃.18H₂O added, Target content of Al incellulose, grams ppm 0.94 500 1.87 1000 3.74 2000 5.62 3000 7.50 40009.37 5000 11.25 6000 14.06 7500 15.00 8000 18.75 10000

Example 46 The Effect of Various Fatty Acids on the Hydrophobicity ofthe Treated Cellulose

Handsheets with various aluminum contents were formed on laboratoryequipment using the cellulose pulp samples prepared as described inExample 45. The handsheets were coated with various sodium soapsolutions by spraying. The concentration of each soap solution was 1%and the resultant average soap add-on was 10 g/kg dry weight ofcellulose. All sodium soap solutions were warmed to 70° C. to obtainhomogenous liquids, and then were sprayed evenly on the surface of thehandsheets. The coated handsheets were dried at 120° C. for 5 min. Thetime of drying was established for 5 min, as it was enough to obtainconstant mass of the sample. The hydrophobicity of the dry handsheetswas examined by contact angle measurements as described in Example 43.The results are illustrated in FIG. 12.

Example 47 Hydrophobic Cellulosic Fibers with Reduced Water Retention

Cellulose pulp (Buckeye Technologies Inc.) with aluminum content of 7000ppm was prepared according to the lab procedure described in Example 45.Handsheets of basis weight approx. 300 g/m² were formed using labforming equipment and then sprayed with citric acid solutions beforedrying. The concentrations of citric acid solutions were 1%, 4% and 10%.The citric acid add-on levels were, respectively: 4.3, 17.7 and 43.7 gper kg of cellulose. The handsheets were dried at 160° C. for 15 minutesand then sprayed with an aqueous solution of 1% sodium stearate byweight, preheated to 70° C. The add-on level of aluminum stearate was 10g (dry weight) per kg cellulose. The samples were dried again at atemperature of 120° C. for 5 min to constant mass. Water retention value(WRV) was determined at each step of the process. The results of the WRVanalyses are summarized in Table 10.

TABLE 10 Properties of cellulose after additional spraying with sodiumstearate solution and WRV of cellulose after drying, % Amount ofspraying with citric acid Cellulose citric acid and drying at 160° C., %WRV of at 7000 ppm Al Concentration Cellulose Cellulose celluloseContact in application Add-on, control at 7000 ppm control angle,solution, % g/kg (0 ppm Al) Al (0 ppm Al) WRV, % deg 0 0 98 93 93 82 122 70 68 65 47 113 4 88 64 60 61 41 111 10 220 57 59 55 39 115

The following conclusions can be drawn from the data in Table 10:

-   -   WRV is practically not affected by the presence of Al in the        fiber    -   The efficiency of the cross-linking reaction depends on citric        acid add-on level. A decrease of WRV is observed with increased        addition of citric acid.    -   A further decrease in WRV can be obtained as a result of the        treatment of the cured cellulose with sodium stearate.

Example 48 Hydrophobic Cellulose Obtained by Pre-Swelling of the Fibersand Hydrophobic Treatment

Cellulose in an amount of 2.5 g was added to 500 ml of 9% NaOH solutionto make a slurry at consistency of 5%. After cooling the mixture to 15°C. aluminum sulfate in an amount of 6.14 g was added to achieve a targetAl content in cellulose of 10000 ppm. Then an aqueous solution ofsulfuric acid at a concentration of 10% by weight was added to adjustthe pH to 5.7 and precipitate Al(OH)₃ within the swollen fibers. Theexcess amount of the liquid phase was removed (about ¾ of liquid volume)and 200 ml of 0.1% by weight of aqueous solution of stearic sodium soapwas added. Then a handsheet (300 g/m²) was formed and dried it at 120°C. for 15 min. The WRV of the obtained sample was 49% and the contactangle was 103°. The sample was then disintegrated and rinsed with 10liters distilled water (5 times by 2 liters of distilled water) anddried again at 120° C. for 15 min. The final WRV of thus preparedcellulose was 54% and the contact angle 101°.

Example 49 Hydrophobic Cellulose Obtained Using Zirconium Salt

A slurry was made using 152 g dry cellulose in 6 liters demineralizedwater. An aqueous solution of sulfuric acid at 10% by weight was thenused to adjust the pH to 3.5-4.0. Subsequent to that 2.86 g ZrOCl₂*8H₂Owas added to the slurry to obtain the target content of Zr in celluloseat 5000 ppm. The slurry was agitated for about 15 minutes andtransferred to a bucket with 13 liters demineralized water and the pHadjusted to 6.0-6.5 with an aqueous solution of sodium hydroxide at aconcentration of 10% by weight. Thus obtained cellulose slurry was usedto form handsheets having a basis weight of about 300 g/m². The sheetswere dried at 120° C. and then coated with 1% by weight aqueous solutionof sodium stearate previously warmed to 70° C. The add-on of the sodiumsoap on the sheet was at 10 g/kg cellulose. The contact angle of thetreated sheet was 112°.

Example 50 Hydrophobic Cellulose Obtained by Direct Treatment withAluminum Stearate

A cellulose sheet having a basis weight of about 300 g/m2 was coatedwith powdered aluminum stearate in an amount of 113.7 g per 1 kgcellulose to obtain a target content of Al in cellulose at 7000 ppm. Thetreated sheet was then cured in an oven at 130° C. for 5 minutes. Thecontact angle of the cured sheet was 121°.

Example 51 Treatment of Cellulose Containing Al with Stearic Acid onSynthetic Fiber Carrier

A slurry of cellulose with deposited aluminum hydroxide was prepared asdescribed in Example 45 to get a target Al content in cellulose at 7000ppm. The slurry was vigorously agitated and polypropylene fibers cut to3 mm were added to it in an amount of 3 g per 1 kg dry cellulose. Thepolypropylene fibers were made at Akademia Techniczno-Humanistyczna,Bielsko-Biala, Poland, and contained about 30% by weight of stearicacid. The obtained slurry of the blend of the cellulosic fibers with thepolypropylene fibers was used to form handsheets on laboratory wetequipment and dried at 160° C. for 15 minutes. The contact angle of thecured sheet was 110°.

The present invention is not to be limited in scope by the specificembodiments described herein. Indeed, various modifications of theinvention in addition to those described herein will become apparent tothose skilled in the art from the foregoing description and theaccompanying figures. Such modifications are intended to fall within thescope of the appended claims.

Patents, patent applications, publications, product descriptions, andprotocols are cited throughout this application, the disclosures ofwhich are incorporated by reference herein in their entireties for allpurposes.

What is claimed is:
 1. A fibrous material comprising a blend of fibers,wherein the blend of fibers comprises: (a) cellulosic fibers bound witha dissociating polyvalent cation-containing compound; wherein thepolyvalent cation-containing compound is present in an amount from about0.1 weight percent to about 20 weight percent based on the dry weight ofthe cellulosic fiber prior to treatment with the bound polyvalentcation-containing compound; and (b) synthetic fibers coated with a fattyacid containing compound, wherein substantially no polyvalent cation ispresent on the synthetic fibers; and wherein the fibrous material ishydrophobic.
 2. The fibrous material of claim 1, wherein the fatty acidcontaining compound is selected from the group consisting of sodiumoleate, methyl oleate, sodium laurate, oleic acid, stearic acid, andmixtures thereof.
 3. The fibrous material of claim 1, wherein thepolyvalent cation containing compound is a polyvalent metal ion salt. 4.The fibers of claim 3, wherein the polyvalent metal is selected from thegroup consisting of aluminum, iron, tin, and mixtures thereof.
 5. Thefibers of claim 4, wherein the polyvalent metal is aluminum.
 6. Thefibers of claim 3, wherein the polyvalent salt is selected from thegroup consisting of aluminum chloride, aluminum hydroxide, aluminumsulfate, and mixtures thereof.
 7. The fibrous material of claim 1,wherein the contact angle of fibers in the blend of fibers is greaterthan 90°.
 8. The fibrous material of claim 1, further comprising one ormore fillers.
 9. The fibrous material of claim 1, wherein the cellulosicfibers are cross linked and optionally treating the fibers with across-linking agent.
 10. The fibrous material of claim 9, wherein thecross-linking agent is applied with thermal radiation.